diff --git a/CHANGES b/CHANGES
index ca6b363a9f9..159640a0491 100644
--- a/CHANGES
+++ b/CHANGES
@@ -67,6 +67,31 @@
 
 - Fix loading of `.yml` files with `tmuxp convert`, thank you @kalixi! (#725)
 
+#### Internal API
+
+- #752: Command structure (internal API)
+
+  To pave the way for per-command options such as `enter: false` (#52), commands are now a different format:
+
+  Before, [`str`](str):
+
+  ```python
+  "echo hello"
+  ```
+
+  After, [`dict`](dict):
+
+  ```python
+  {
+     "cmd": "echo hello"
+  }
+  ```
+
+  This is purely internal. Normal usage should be the same since the
+  configuration emits the equivalent result.
+
+- #752: Configuration parsing refactorings
+
 #### Development
 
 - Run through black + isort with string normalization (#738). This way we can
diff --git a/tests/fixtures/config/expand1.py b/tests/fixtures/config/expand1.py
index d431741ef73..71e8e0704f3 100644
--- a/tests/fixtures/config/expand1.py
+++ b/tests/fixtures/config/expand1.py
@@ -36,39 +36,42 @@
         {
             "window_name": "editor",
             "panes": [
-                {"shell_command": ["vim", "top"]},
-                {"shell_command": ["vim"]},
-                {"shell_command": ['cowsay "hey"']},
+                {"shell_command": [{"cmd": "vim"}, {"cmd": "top"}]},
+                {"shell_command": [{"cmd": "vim"}]},
+                {"shell_command": [{"cmd": 'cowsay "hey"'}]},
             ],
             "layout": "main-verticle",
         },
         {
             "window_name": "logging",
-            "panes": [{"shell_command": ["tail -F /var/log/syslog"]}],
+            "panes": [{"shell_command": [{"cmd": "tail -F /var/log/syslog"}]}],
         },
         {
             "start_directory": "/var/log",
             "options": {"automatic-rename": True},
-            "panes": [{"shell_command": ["htop"]}, {"shell_command": ["vim"]}],
+            "panes": [
+                {"shell_command": [{"cmd": "htop"}]},
+                {"shell_command": [{"cmd": "vim"}]},
+            ],
         },
         {
             "start_directory": os.path.normpath(
                 os.path.join(os.path.expanduser("~"), "./")
             ),
-            "panes": [{"shell_command": ["pwd"]}],
+            "panes": [{"shell_command": [{"cmd": "pwd"}]}],
         },
         {
             "start_directory": os.path.normpath(
                 os.path.join(os.path.expanduser("~"), "./asdf")
             ),
-            "panes": [{"shell_command": ["pwd"]}],
+            "panes": [{"shell_command": [{"cmd": "pwd"}]}],
         },
         {
             "start_directory": os.path.normpath(
                 os.path.join(os.path.expanduser("~"), "../")
             ),
-            "panes": [{"shell_command": ["pwd"]}],
+            "panes": [{"shell_command": [{"cmd": "pwd"}]}],
         },
-        {"panes": [{"shell_command": ["top"]}]},
+        {"panes": [{"shell_command": [{"cmd": "top"}]}]},
     ],
 }
diff --git a/tests/fixtures/config/expand2-expanded.yaml b/tests/fixtures/config/expand2-expanded.yaml
index 0fe5bbd3d9b..e407146427f 100644
--- a/tests/fixtures/config/expand2-expanded.yaml
+++ b/tests/fixtures/config/expand2-expanded.yaml
@@ -6,27 +6,27 @@ windows:
   focus: true
   panes:
   - shell_command:
-    - cd ~
+    - cmd: cd ~
   - shell_command:
-    - cd /usr
+    - cmd: cd /usr
     focus: true
   - shell_command:
-    - cd ~
-    - echo "moo"
-    - top
+    - cmd: cd ~
+    - cmd: echo "moo"
+    - cmd: top
 - window_name: window 2
   panes:
   - shell_command:
-    - top
+    - cmd: top
     focus: true
   - shell_command:
-    - echo "hey"
+    - cmd: echo "hey"
   - shell_command:
-    - echo "moo"
+    - cmd: echo "moo"
 - window_name: window 3
   panes:
   - shell_command:
-    - cd /
+    - cmd: cd /
     focus: true
   - shell_command: []
   - shell_command: []
diff --git a/tests/fixtures/config/expand_blank.py b/tests/fixtures/config/expand_blank.py
index 78343ca7110..4d0dad3b490 100644
--- a/tests/fixtures/config/expand_blank.py
+++ b/tests/fixtures/config/expand_blank.py
@@ -20,9 +20,9 @@
         {
             "window_name": "Empty string (return)",
             "panes": [
-                {"shell_command": [""]},
-                {"shell_command": [""]},
-                {"shell_command": [""]},
+                {"shell_command": [{"cmd": ""}]},
+                {"shell_command": [{"cmd": ""}]},
+                {"shell_command": [{"cmd": ""}]},
             ],
         },
         {
diff --git a/tests/fixtures/config/shell_command_before.py b/tests/fixtures/config/shell_command_before.py
index 2f0b1a69660..0f5725e2eec 100644
--- a/tests/fixtures/config/shell_command_before.py
+++ b/tests/fixtures/config/shell_command_before.py
@@ -43,21 +43,27 @@
         {
             "window_name": "editor",
             "start_directory": os.path.expanduser("~"),
-            "shell_command_before": ["source .venv/bin/activate"],
+            "shell_command_before": {
+                "shell_command": [{"cmd": "source .venv/bin/activate"}]
+            },
             "panes": [
-                {"shell_command": ["vim"]},
+                {"shell_command": [{"cmd": "vim"}]},
                 {
-                    "shell_command_before": ["rbenv local 2.0.0-p0"],
-                    "shell_command": ['cowsay "hey"'],
+                    "shell_command_before": {
+                        "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+                    },
+                    "shell_command": [{"cmd": 'cowsay "hey"'}],
                 },
             ],
             "layout": "main-verticle",
         },
         {
-            "shell_command_before": ["rbenv local 2.0.0-p0"],
+            "shell_command_before": {
+                "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+            },
             "window_name": "logging",
             "panes": [
-                {"shell_command": ["tail -F /var/log/syslog"]},
+                {"shell_command": [{"cmd": "tail -F /var/log/syslog"}]},
                 {"shell_command": []},
             ],
         },
@@ -65,13 +71,18 @@
             "window_name": "shufu",
             "panes": [
                 {
-                    "shell_command_before": ["rbenv local 2.0.0-p0"],
-                    "shell_command": ["htop"],
+                    "shell_command_before": {
+                        "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+                    },
+                    "shell_command": [{"cmd": "htop"}],
                 }
             ],
         },
-        {"options": {"automatic-rename": True}, "panes": [{"shell_command": ["htop"]}]},
-        {"panes": [{"shell_command": ["top"]}]},
+        {
+            "options": {"automatic-rename": True},
+            "panes": [{"shell_command": [{"cmd": "htop"}]}],
+        },
+        {"panes": [{"shell_command": [{"cmd": "top"}]}]},
     ],
 }
 
@@ -82,27 +93,43 @@
         {
             "window_name": "editor",
             "start_directory": os.path.expanduser("~"),
-            "shell_command_before": ["source .venv/bin/activate"],
+            "shell_command_before": {
+                "shell_command": [{"cmd": "source .venv/bin/activate"}]
+            },
             "panes": [
-                {"shell_command": ["source .venv/bin/activate", "vim"]},
                 {
-                    "shell_command_before": ["rbenv local 2.0.0-p0"],
                     "shell_command": [
-                        "source .venv/bin/activate",
-                        "rbenv local 2.0.0-p0",
-                        'cowsay "hey"',
+                        {"cmd": "source .venv/bin/activate"},
+                        {"cmd": "vim"},
+                    ]
+                },
+                {
+                    "shell_command_before": {
+                        "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+                    },
+                    "shell_command": [
+                        {"cmd": "source .venv/bin/activate"},
+                        {"cmd": "rbenv local 2.0.0-p0"},
+                        {"cmd": 'cowsay "hey"'},
                     ],
                 },
             ],
             "layout": "main-verticle",
         },
         {
-            "shell_command_before": ["rbenv local 2.0.0-p0"],
+            "shell_command_before": {
+                "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+            },
             "start_directory": "/",
             "window_name": "logging",
             "panes": [
-                {"shell_command": ["rbenv local 2.0.0-p0", "tail -F /var/log/syslog"]},
-                {"shell_command": ["rbenv local 2.0.0-p0"]},
+                {
+                    "shell_command": [
+                        {"cmd": "rbenv local 2.0.0-p0"},
+                        {"cmd": "tail -F /var/log/syslog"},
+                    ]
+                },
+                {"shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]},
             ],
         },
         {
@@ -110,16 +137,18 @@
             "window_name": "shufu",
             "panes": [
                 {
-                    "shell_command_before": ["rbenv local 2.0.0-p0"],
-                    "shell_command": ["rbenv local 2.0.0-p0", "htop"],
+                    "shell_command_before": {
+                        "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}]
+                    },
+                    "shell_command": [{"cmd": "rbenv local 2.0.0-p0"}, {"cmd": "htop"}],
                 }
             ],
         },
         {
             "start_directory": "/",
             "options": {"automatic-rename": True},
-            "panes": [{"shell_command": ["htop"]}],
+            "panes": [{"shell_command": [{"cmd": "htop"}]}],
         },
-        {"start_directory": "/", "panes": [{"shell_command": ["top"]}]},
+        {"start_directory": "/", "panes": [{"shell_command": [{"cmd": "top"}]}]},
     ],
 }
diff --git a/tests/fixtures/config/shell_command_before_session-expected.yaml b/tests/fixtures/config/shell_command_before_session-expected.yaml
index 4e1e3eb49a0..dd55247c886 100644
--- a/tests/fixtures/config/shell_command_before_session-expected.yaml
+++ b/tests/fixtures/config/shell_command_before_session-expected.yaml
@@ -1,23 +1,24 @@
 shell_command_before:
-  - 'echo "hi"'
+  shell_command:
+    - cmd: 'echo "hi"'
 session_name: 'test'
 windows:
 - window_name: editor
   panes:
   - shell_command:
-    - 'echo "hi"'
-    - vim
-    - :Ex
+    - cmd: 'echo "hi"'
+    - cmd: vim
+    - cmd: :Ex
   - shell_command:
-    - 'echo "hi"'
+    - cmd: 'echo "hi"'
   - shell_command:
-    - 'echo "hi"'
-    - cd /usr
+    - cmd: 'echo "hi"'
+    - cmd: cd /usr
 - window_name: logging
   panes:
   - shell_command:
-    - 'echo "hi"'
+    - cmd: 'echo "hi"'
   - shell_command:
-    - 'echo "hi"'
-    - top
-    - emacs
+    - cmd: 'echo "hi"'
+    - cmd: top
+    - cmd: emacs
diff --git a/tests/fixtures/config/trickle.py b/tests/fixtures/config/trickle.py
index 7792ba425a9..595ee563604 100644
--- a/tests/fixtures/config/trickle.py
+++ b/tests/fixtures/config/trickle.py
@@ -5,14 +5,17 @@
         {
             "window_name": "editor",
             "start_directory": "log",
-            "panes": [{"shell_command": ["vim"]}, {"shell_command": ['cowsay "hey"']}],
+            "panes": [
+                {"shell_command": [{"cmd": "vim"}]},
+                {"shell_command": [{"cmd": 'cowsay "hey"'}]},
+            ],
             "layout": "main-verticle",
         },
         {
             "window_name": "logging",
             "start_directory": "~",
             "panes": [
-                {"shell_command": ["tail -F /var/log/syslog"]},
+                {"shell_command": [{"cmd": "tail -F /var/log/syslog"}]},
                 {"shell_command": []},
             ],
         },
@@ -26,14 +29,17 @@
         {
             "window_name": "editor",
             "start_directory": "/var/log",
-            "panes": [{"shell_command": ["vim"]}, {"shell_command": ['cowsay "hey"']}],
+            "panes": [
+                {"shell_command": [{"cmd": "vim"}]},
+                {"shell_command": [{"cmd": 'cowsay "hey"'}]},
+            ],
             "layout": "main-verticle",
         },
         {
             "start_directory": "~",
             "window_name": "logging",
             "panes": [
-                {"shell_command": ["tail -F /var/log/syslog"]},
+                {"shell_command": [{"cmd": "tail -F /var/log/syslog"}]},
                 {"shell_command": []},
             ],
         },
diff --git a/tests/fixtures/workspacebuilder/focus_and_pane.yaml b/tests/fixtures/workspacebuilder/focus_and_pane.yaml
index e6917c3ff14..d7e9b5d9903 100644
--- a/tests/fixtures/workspacebuilder/focus_and_pane.yaml
+++ b/tests/fixtures/workspacebuilder/focus_and_pane.yaml
@@ -5,26 +5,27 @@ windows:
   focus: true
   panes:
   - shell_command:
-    - cd ~
+    - cmd: cd ~
   - shell_command:
-    - cd /usr
+    - cmd: cd /usr
     focus: true
   - shell_command:
-    - cd ~
-    - echo "moo"
-    - top
+    - cmd: cd ~
+    - cmd: echo "moo"
+    - cmd: top
 - window_name: window 2
   panes:
   - shell_command:
-    - top
+    - cmd: top
     focus: true
   - shell_command:
-    - echo "hey"
+    - cmd: echo "hey"
   - shell_command:
-    - echo "moo"
+    - cmd: echo "moo"
 - window_name: window 3
   panes:
-  - shell_command: cd /
+  - shell_command: 
+    - cmd: cd /
     focus: true
   - pane
   - pane
diff --git a/tests/fixtures/workspacebuilder/plugin_bs.yaml b/tests/fixtures/workspacebuilder/plugin_bs.yaml
index a04d6eb3f30..5785afb4203 100644
--- a/tests/fixtures/workspacebuilder/plugin_bs.yaml
+++ b/tests/fixtures/workspacebuilder/plugin_bs.yaml
@@ -5,11 +5,11 @@ windows:
 - window_name: editor
   layout: tiled
   shell_command_before:
-    - cd ~/
+    - cmd: cd ~/
   panes:
     - shell_command:
-        - cd /var/log
-        - ls -al | grep \.log
-    - echo hello
-    - echo hello
-    - echo hello
+      - cmd: cd /var/log
+      - cmd: ls -al | grep \.log
+    - cmd: echo hello
+    - cmd: echo hello
+    - cmd: echo hello
diff --git a/tests/fixtures/workspacebuilder/three_pane.yaml b/tests/fixtures/workspacebuilder/three_pane.yaml
index f883fc2b36a..08995253252 100644
--- a/tests/fixtures/workspacebuilder/three_pane.yaml
+++ b/tests/fixtures/workspacebuilder/three_pane.yaml
@@ -5,8 +5,8 @@ windows:
   layout: main-horizontal
   panes:
   - shell_command:
-    - vim
+    - cmd: vim
   - shell_command:
-    - echo "hey"
+    - cmd: echo "hey"
   - shell_command:
-    - echo "moo"
+    - cmd: echo "moo"
diff --git a/tests/fixtures/workspacebuilder/three_windows.yaml b/tests/fixtures/workspacebuilder/three_windows.yaml
index e0c8286f851..b883a7da57f 100644
--- a/tests/fixtures/workspacebuilder/three_windows.yaml
+++ b/tests/fixtures/workspacebuilder/three_windows.yaml
@@ -3,12 +3,12 @@ windows:
 - window_name: first
   panes:
     - shell_command:
-      - echo 'first window'
+      - cmd: echo 'first window'
 - window_name: second
   panes:
     - shell_command:
-      - echo 'second window'
+      - cmd: echo 'second window'
 - window_name: third
   panes:
     - shell_command:
-      - echo 'third window'
+      - cmd: echo 'third window'
diff --git a/tests/fixtures/workspacebuilder/two_pane.yaml b/tests/fixtures/workspacebuilder/two_pane.yaml
index be083ff48b8..9bb96e70f37 100644
--- a/tests/fixtures/workspacebuilder/two_pane.yaml
+++ b/tests/fixtures/workspacebuilder/two_pane.yaml
@@ -4,15 +4,15 @@ windows:
 - layout: main-vertical
   panes:
   - shell_command:
-    - vim
+    - cmd: vim
   - shell_command:
-    - echo "hey"
+    - cmd: echo "hey"
   window_name: editor
 - panes:
   - shell_command:
-    - tail | echo 'hi'
+    - cmd: tail | echo 'hi'
   window_name: logging
 - window_name: test
   panes:
   - shell_command:
-    - htop
+    - cmd: htop
diff --git a/tests/fixtures/workspacebuilder/two_windows.yaml b/tests/fixtures/workspacebuilder/two_windows.yaml
index 0f1d40f34a9..490382fe5f3 100644
--- a/tests/fixtures/workspacebuilder/two_windows.yaml
+++ b/tests/fixtures/workspacebuilder/two_windows.yaml
@@ -3,8 +3,8 @@ windows:
 - window_name: first
   panes:
     - shell_command:
-      - echo 'first window'
+      - cmd: echo 'first window'
 - window_name: second
   panes:
     - shell_command:
-      - echo 'second window'
+      - cmd: echo 'second window'
diff --git a/tests/fixtures/workspacebuilder/window_automatic_rename.yaml b/tests/fixtures/workspacebuilder/window_automatic_rename.yaml
index 9b74b4fe7f5..08329afcfea 100644
--- a/tests/fixtures/workspacebuilder/window_automatic_rename.yaml
+++ b/tests/fixtures/workspacebuilder/window_automatic_rename.yaml
@@ -6,9 +6,9 @@ windows:
     automatic-rename: on
   panes:
   - shell_command:
-    - sh
+    - cmd: sh
     start_directory: '~'
   - shell_command:
-    - echo "hey"
+    - cmd: echo "hey"
   - shell_command:
-    - echo "moo"
+    - cmd: echo "moo"
diff --git a/tests/fixtures/workspacefreezer/sampleconfig.yaml b/tests/fixtures/workspacefreezer/sampleconfig.yaml
index b7a6d010703..fb8b11e3e22 100644
--- a/tests/fixtures/workspacefreezer/sampleconfig.yaml
+++ b/tests/fixtures/workspacefreezer/sampleconfig.yaml
@@ -4,18 +4,18 @@ windows:
 - layout: main-vertical
   panes:
   - shell_command:
-    - vim
+    - cmd: vim
     start_directory: '~'
   - shell_command:
-    - echo "hey"
-    - cd ../
+    - cmd: echo "hey"
+    - cmd: cd ../
   window_name: editor
 - panes:
   - shell_command:
-    - pane
+    - cmd: pane
     start_directory: /usr/bin
   window_name: logging
 - window_name: test
   panes:
   - shell_command:
-    - top
+    - cmd: top
diff --git a/tests/test_config.py b/tests/test_config.py
index a89b3631548..1352d0034c7 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -395,7 +395,10 @@ def test_replaces_env_variables(monkeypatch):
     monkeypatch.setenv(str(env_key), str(env_val))
     sconfig = config.expand(sconfig)
     assert "%s/test" % env_val == sconfig["start_directory"]
-    assert "%s/test2" % env_val in sconfig["shell_command_before"]
+    assert (
+        "%s/test2" % env_val
+        in sconfig["shell_command_before"]["shell_command"][0]["cmd"]
+    )
     assert "%s/test3" % env_val == sconfig["before_script"]
     assert "hi - %s" % env_val == sconfig["session_name"]
     assert "%s/moo" % env_val == sconfig["global_options"]["default-shell"]
diff --git a/tmuxp/config.py b/tmuxp/config.py
index f8b8ec5deab..7d5cb2cae06 100644
--- a/tmuxp/config.py
+++ b/tmuxp/config.py
@@ -114,7 +114,7 @@ def expandshell(_path):
     """
     Return expanded path based on user's ``$HOME`` and ``env``.
 
-    :py:func:`os.path.expanduser` and :py:func:`os.path.expandvars`
+    :py:func:`os.path.expanduser` and :py:func:`os.path.expandvar`s
 
     Parameters
     ----------
@@ -175,24 +175,31 @@ def inline(session_config):
 def expand_cmd(p: Dict) -> Dict:
     if isinstance(p, str):
         p = {"shell_command": [p]}
+    elif isinstance(p, list):
+        p = {"shell_command": p}
     elif not p:
         p = {"shell_command": []}
 
     assert isinstance(p, dict)
     if "shell_command" in p:
-        cmd = p["shell_command"]
+        cmds = p["shell_command"]
 
         if isinstance(p["shell_command"], str):
-            cmd = [cmd]
+            cmds = [cmds]
 
-        if not cmd or any(a == cmd for a in [None, "blank", "pane"]):
-            cmd = []
+        if not cmds or any(a == cmds for a in [None, "blank", "pane"]):
+            cmds = []
 
-        if isinstance(cmd, list) and len(cmd) == int(1):
-            if any(a in cmd for a in [None, "blank", "pane"]):
-                cmd = []
+        if isinstance(cmds, list) and len(cmds) == int(1):
+            if any(a in cmds for a in [None, "blank", "pane"]):
+                cmds = []
 
-        p["shell_command"] = cmd
+        for cmd_idx, cmd in enumerate(cmds):
+            if isinstance(cmd, str):
+                cmds[cmd_idx] = {"cmd": cmd}
+            cmds[cmd_idx]["cmd"] = expandshell(cmds[cmd_idx]["cmd"])
+
+        p["shell_command"] = cmds
     else:
         p["shell_command"] = []
     return p
@@ -295,19 +302,10 @@ def expand(session_config, cwd=None, parent=None):
     ):
         session_config["shell_command"] = [session_config["shell_command"]]
 
-    if "shell_command_before" in session_config and isinstance(
-        session_config["shell_command_before"], str
-    ):
-        session_config["shell_command_before"] = [
-            session_config["shell_command_before"]
-        ]
+    if "shell_command_before" in session_config:
+        shell_command_before = session_config["shell_command_before"]
 
-    if "shell_command_before" in session_config and isinstance(
-        session_config["shell_command_before"], list
-    ):
-        session_config["shell_command_before"] = [
-            expandshell(scmd) for scmd in session_config["shell_command_before"]
-        ]
+        session_config["shell_command_before"] = expand_cmd(shell_command_before)
 
     # recurse into window and pane config items
     if "windows" in session_config:
@@ -390,11 +388,17 @@ def trickle(session_config):
 
             # Prepend shell_command_before to commands
             if "shell_command_before" in session_config:
-                commands_before.extend(session_config["shell_command_before"])
+                commands_before.extend(
+                    session_config["shell_command_before"]["shell_command"]
+                )
             if "shell_command_before" in window_config:
-                commands_before.extend(window_config["shell_command_before"])
+                commands_before.extend(
+                    window_config["shell_command_before"]["shell_command"]
+                )
             if "shell_command_before" in pane_config:
-                commands_before.extend(pane_config["shell_command_before"])
+                commands_before.extend(
+                    pane_config["shell_command_before"]["shell_command"]
+                )
 
             if "shell_command" in pane_config:
                 commands_before.extend(pane_config["shell_command"])
diff --git a/tmuxp/workspacebuilder.py b/tmuxp/workspacebuilder.py
index a470ea07aaf..a51e13209b7 100644
--- a/tmuxp/workspacebuilder.py
+++ b/tmuxp/workspacebuilder.py
@@ -365,7 +365,7 @@ def get_pane_shell():
             enter = pconf.get("enter", True)
 
             for cmd in pconf["shell_command"]:
-                p.send_keys(cmd, suppress_history=suppress, enter=enter)
+                p.send_keys(cmd["cmd"], suppress_history=suppress, enter=enter)
 
             if "focus" in pconf and pconf["focus"]:
                 w.select_pane(p["pane_id"])