diff --git a/src/pipecat/services/assemblyai/models.py b/src/pipecat/services/assemblyai/models.py
new file mode 100644
index 000000000..6a0179c3d
--- /dev/null
+++ b/src/pipecat/services/assemblyai/models.py
@@ -0,0 +1,61 @@
+from typing import List, Literal, Optional
+
+from pydantic import BaseModel, Field
+
+
+class Word(BaseModel):
+    """Represents a single word in a transcription with timing and confidence."""
+
+    start: int
+    end: int
+    text: str
+    confidence: float
+    word_is_final: bool = Field(..., alias="word_is_final")
+
+
+class BaseMessage(BaseModel):
+    """Base class for all AssemblyAI WebSocket messages."""
+
+    type: str
+
+
+class BeginMessage(BaseMessage):
+    """Message sent when a new session begins."""
+
+    type: Literal["Begin"] = "Begin"
+    id: str
+    expires_at: int
+
+
+class TurnMessage(BaseMessage):
+    """Message containing transcription data for a turn of speech."""
+
+    type: Literal["Turn"] = "Turn"
+    turn_order: int
+    turn_is_formatted: bool
+    end_of_turn: bool
+    transcript: str
+    end_of_turn_confidence: float
+    words: List[Word]
+
+
+class TerminationMessage(BaseMessage):
+    """Message sent when the session is terminated."""
+
+    type: Literal["Termination"] = "Termination"
+    audio_duration_seconds: float
+    session_duration_seconds: float
+
+
+# Union type for all possible message types
+AnyMessage = BeginMessage | TurnMessage | TerminationMessage
+
+
+class AssemblyAIConnectionParams(BaseModel):
+    sample_rate: int = 16000
+    encoding: Literal["pcm_s16le", "pcm_mulaw"] = "pcm_s16le"
+    formatted_finals: bool = False
+    word_finalization_max_wait_time: Optional[int] = None
+    end_of_turn_confidence_threshold: Optional[float] = None
+    min_end_of_turn_silence_when_confident: Optional[int] = None
+    max_turn_silence: Optional[int] = None