diff --git a/catmux/session.py b/catmux/session.py
index 5cea1aa..ef5c2e6 100644
--- a/catmux/session.py
+++ b/catmux/session.py
@@ -70,8 +70,8 @@ def init_from_yaml(self, yaml_data):
         """Initialize config directly by an already loaded yaml structure."""
 
         self.__yaml_data = yaml_data
-        self._parse_common()
         self._parse_parameters()
+        self._parse_common()
         self._parse_windows()
 
     def run(self, parent_server: libtmux.Server, debug=False):
@@ -101,11 +101,28 @@ def _parse_common(self):
         if "common" in self.__yaml_data and self.__yaml_data["common"]:
             common = self.__yaml_data["common"]
             if "before_commands" in common and common["before_commands"]:
-                self._before_commands = common["before_commands"]
+                # self._before_commands = common["before_commands"]
+                self._parse_before_commands(common["before_commands"])
 
             if "default_window" in common and common["default_window"]:
                 self._default_window = common["default_window"]
 
+
+    def _parse_before_commands(self, commands):
+        command_list = []
+        for command in commands:
+            if isinstance(command, str):
+                command_list.append(command)
+            elif isinstance(command, dict):
+                conditional_param = command.get('if')
+                print(conditional_param)
+                if conditional_param not in self._parameters:
+                    raise RuntimeError
+                elif self._parameters[conditional_param]:
+                    command_list.append(command)
+        self._before_commands = command_list
+
+
     def _parse_overwrites(self, data_string):
         """Separates a comma-separated list of foo=val1,bar=val2 into a dictionary."""
         if data_string is None:
diff --git a/test/test_parsing.py b/test/test_parsing.py
index 353f4ac..f4d495a 100644
--- a/test/test_parsing.py
+++ b/test/test_parsing.py
@@ -93,6 +93,29 @@ def test_empty_before_commands():
     assert session._default_window == None
 
 
+def test_conditional_before_commands():
+    CONFIG = """common:
+    before_commands:
+    - if: param_true
+      command: echo "true"
+    - if: param_false_
+      command: echo "false"
+windows:
+    - name: left-right
+      splits:
+        - commands:
+          - echo "left"
+    - name: foo
+      splits:
+        - commands:
+          - echo "left"
+"""
+    session = Session("name")
+    session.init_from_yaml(yaml.safe_load(CONFIG))
+
+    assert len(session._before_commands) == 1
+
+
 def test_missing_parameter_for_if_unless():
     CONFIG = """common:
     before_commands: