diff --git a/convokit/genai/llmprompttransformer.py b/convokit/genai/llmprompttransformer.py
index 1b48ea7a..241db40c 100644
--- a/convokit/genai/llmprompttransformer.py
+++ b/convokit/genai/llmprompttransformer.py
@@ -1,5 +1,7 @@
-from typing import Optional, Union, Callable, Dict, Any
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from typing import Optional, Union, Callable, Dict, Any, Iterable
 from convokit import Transformer, Corpus, Conversation, Speaker, Utterance
+from tqdm.auto import tqdm
 from .factory import get_llm_client
 from .genai_config import GenAIConfigManager
 
@@ -20,6 +22,7 @@ class LLMPromptTransformer(Transformer):
     :param selector: Optional function to filter which objects to process. Defaults to processing all objects
     :param config_manager: GenAIConfigManager instance for LLM API key management
     :param llm_kwargs: Additional keyword arguments to pass to the LLM client
+    :param num_workers: Number of worker threads to use for LLM calls. Defaults to 1 (sequential)
     """
 
     def __init__(
@@ -35,6 +38,7 @@ def __init__(
         ] = None,
         config_manager: Optional[GenAIConfigManager] = None,
         llm_kwargs: Optional[Dict[str, Any]] = None,
+        num_workers: int = 1,
     ):
         self.provider = provider
         self.model = model
@@ -45,10 +49,14 @@ def __init__(
         self.selector = selector or (lambda obj: True)
         self.config_manager = config_manager or GenAIConfigManager()
         self.llm_kwargs = llm_kwargs or {}
+        self.num_workers = num_workers
 
         if model is not None:
             self.llm_kwargs["model"] = model
 
+        if num_workers < 1:
+            raise ValueError("num_workers must be at least 1")
+
         if object_level not in ["conversation", "speaker", "utterance", "corpus"]:
             raise ValueError(
                 f"Invalid object_level: {object_level}. Must be one of: conversation, speaker, utterance, corpus"
@@ -88,6 +96,39 @@ def _process_object(self, obj: Union[Corpus, Conversation, Speaker, Utterance])
             print(f"Error processing {self.object_level} {obj.id}: {e}")
             obj.add_meta(self.metadata_name, None)
 
+    def _transform_object(self, obj: Union[Corpus, Conversation, Speaker, Utterance]) -> None:
+        """
+        Apply selector logic and process a single object.
+
+        :param obj: Object to transform
+        """
+        if self.selector(obj):
+            self._process_object(obj)
+        else:
+            obj.add_meta(self.metadata_name, None)
+
+    def _transform_objects(
+        self,
+        objects: Iterable[Union[Conversation, Speaker, Utterance]],
+        desc: str,
+    ) -> None:
+        """
+        Transform a collection of objects, optionally in parallel.
+
+        :param objects: Objects to transform
+        :param desc: Progress bar description
+        """
+        if self.num_workers == 1:
+            for obj in tqdm(objects, desc=desc):
+                self._transform_object(obj)
+            return
+
+        objects = list(objects)
+        with ThreadPoolExecutor(max_workers=self.num_workers) as executor:
+            futures = [executor.submit(self._transform_object, obj) for obj in objects]
+            for future in tqdm(as_completed(futures), total=len(futures), desc=desc):
+                future.result()
+
     def transform(self, corpus: Corpus) -> Corpus:
         """
         Apply the GenAI transformer to the corpus.
@@ -96,25 +137,15 @@ def transform(self, corpus: Corpus) -> Corpus:
         :return: The transformed corpus with LLM responses added as metadata
         """
         if self.object_level == "utterance":
-            for utterance in corpus.iter_utterances():
-                if self.selector(utterance):
-                    self._process_object(utterance)
-                else:
-                    utterance.add_meta(self.metadata_name, None)
+            self._transform_objects(corpus.iter_utterances(), "Applying LLM prompt to utterances")
 
         elif self.object_level == "conversation":
-            for conversation in corpus.iter_conversations():
-                if self.selector(conversation):
-                    self._process_object(conversation)
-                else:
-                    conversation.add_meta(self.metadata_name, None)
+            self._transform_objects(
+                corpus.iter_conversations(), "Applying LLM prompt to conversations"
+            )
 
         elif self.object_level == "speaker":
-            for speaker in corpus.iter_speakers():
-                if self.selector(speaker):
-                    self._process_object(speaker)
-                else:
-                    speaker.add_meta(self.metadata_name, None)
+            self._transform_objects(corpus.iter_speakers(), "Applying LLM prompt to speakers")
 
         elif self.object_level == "corpus":
             if self.selector(corpus):