diff --git a/.vscode/settings.json b/.vscode/settings.json
index aed4db4..bfb00fc 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -3,5 +3,6 @@
         "-s", "-vv", "--runslow",
     ],
     "python.testing.unittestEnabled": false,
-    "python.testing.pytestEnabled": true
+    "python.testing.pytestEnabled": true,
+    "python.defaultInterpreterPath": "~/miniconda3/envs/lmwrapper/bin/python",
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 83e7085..931d9e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ breaking changes, Y is new features or larger non-breaking changes, and Z is sma
 However, it is still pre-1.0 software, and does not claim to
 be super stable.
 
+## [0.16.4.0]
+
+### Added
+- Added metadata field to LmPrompt class with generic type support
 
 ## [0.16.3.0]
 
diff --git a/README.md b/README.md
index edec27e..5cd7cf5 100644
--- a/README.md
+++ b/README.md
@@ -201,6 +201,7 @@ def make_prompts(data) -> list[LmPrompt]:
             max_tokens=10,
             temperature=0,
             cache=True,
+            metadata={"country": country}
         ) 
         for country in data
     ]
@@ -216,9 +217,10 @@ predictions = lm.predict_many(
     #                   the non-batching API at a higher cost.
 ) # The batch is submitted here
 
-for ex, pred in zip(data, predictions):  # Will wait for the batch to complete
-    print(f"Country: {ex} --- Capital: {pred.completion_text}")
-    if ex == "France": assert pred.completion_text == "Paris" 
+for pred in predictions:  # Will wait for the batch to complete
+    country = pred.prompt.metadata['country']
+    print(f"Country: {country} --- Capital: {pred.completion_text}")
+    if country == "France": assert pred.completion_text == "Paris" 
     # ...
 ```
 
@@ -364,7 +366,7 @@ please make a Github Issue.
 - [X] Anthropic interface (basic)
     - [X] Claude system messages
 - [X] Use the huggingface chat templates for chat models if available
-- [ ] Be able to add user metadata to a prompt
+- [X] Be able to add metadata to a prompt
 - [ ] Automatic cache eviction to limit count or disk size (right now have to run a SQL query to delete entries before a certain time or matching your criteria)
 - [ ] Multimodal/images in super easy format (like automatically process pil, opencv, etc)
 - [ ] sort through usage of quantized models
diff --git a/lmwrapper/abstract_predictor.py b/lmwrapper/abstract_predictor.py
index 06b13fb..deea242 100644
--- a/lmwrapper/abstract_predictor.py
+++ b/lmwrapper/abstract_predictor.py
@@ -2,12 +2,13 @@
 from abc import abstractmethod
 from collections.abc import Callable, Iterable
 from sqlite3 import OperationalError
+from typing import TypeVar, Union
 
 from ratemate import RateLimit
 
 from lmwrapper.batch_config import CompletionWindow
 from lmwrapper.sqlcache_struct import BatchPredictionPlaceholder
-from lmwrapper.structs import LM_CHAT_DIALOG_COERCIBLE_TYPES, LmPrediction, LmPrompt
+from lmwrapper.structs import LM_CHAT_DIALOG_COERCIBLE_TYPES, LmPrediction, LmPrompt, T
 
 
 class LmPredictor:
@@ -23,13 +24,13 @@ def __init__(
 
         self._disk_cache = SqlBackedCache(self)
 
-    def find_prediction_class(self, prompt):
-        return LmPrediction
+    def find_prediction_class(self, prompt: LmPrompt[T]):
+        return LmPrediction[T]
 
     def predict(
         self,
-        prompt: LmPrompt | str | LM_CHAT_DIALOG_COERCIBLE_TYPES,
-    ) -> LmPrediction | list[LmPrediction]:
+        prompt: LmPrompt[T] | str | LM_CHAT_DIALOG_COERCIBLE_TYPES,
+    ) -> LmPrediction[T] | list[LmPrediction[T]]:
         prompt = self._cast_prompt(prompt)
         should_cache = self._cache_default if prompt.cache is None else prompt.cache
         if should_cache and prompt.model_internals_request is not None:
@@ -74,7 +75,7 @@ def predict(
             return vals[0]
         return vals
 
-    def _read_cached_values(self, prompt: LmPrompt) -> list[LmPrediction]:
+    def _read_cached_values(self, prompt: LmPrompt[T]) -> list[LmPrediction[T]]:
         """
         Checks the cache for any matches of the prompt. Returns a list
         as if num_completions is >1 we might have multiple items
@@ -101,9 +102,9 @@ def _read_cached_values(self, prompt: LmPrompt) -> list[LmPrediction]:
 
     def predict_many(
         self,
-        prompts: list[LmPrompt],
+        prompts: list[LmPrompt[T]],
         completion_window: CompletionWindow,
-    ) -> Iterable[LmPrediction | list[LmPrediction]]:
+    ) -> Iterable[LmPrediction[T] | list[LmPrediction[T]]]:
         self._validate_predict_many_prompts(prompts)
         for prompt in prompts:
             val = self.predict(prompt)
@@ -125,11 +126,11 @@ def _validate_predict_many_prompts(self, prompts):
 
     def remove_prompt_from_cache(
         self,
-        prompt: str | LmPrompt,
+        prompt: str | LmPrompt[T],
     ) -> bool:
         return self._disk_cache.delete(prompt)
 
-    def _validate_prompt(self, prompt: LmPrompt, raise_on_invalid: bool = True) -> bool:
+    def _validate_prompt(self, prompt: LmPrompt[T], raise_on_invalid: bool = True) -> bool:
         """Called on prediction to make sure the prompt is valid for the model"""
         return True
 
@@ -145,11 +146,11 @@ def supports_token_operations(self) -> bool:
     @abstractmethod
     def _predict_maybe_cached(
         self,
-        prompt: LmPrompt,
-    ) -> list[LmPrediction]:
+        prompt: LmPrompt[T],
+    ) -> LmPrediction[T] | list[LmPrediction[T]]:
         pass
 
-    def _cast_prompt(self, prompt: str | LmPrompt) -> LmPrompt:
+    def _cast_prompt(self, prompt: str | LmPrompt[T] | list) -> LmPrompt[T]:
         if isinstance(prompt, str):
             return LmPrompt(prompt, 100)
         if isinstance(prompt, list):
@@ -180,14 +181,14 @@ def _cast_prompt(self, prompt: str | LmPrompt) -> LmPrompt:
             )
             raise ValueError(msg)
 
-    def estimate_tokens_in_prompt(self, prompt: LmPrompt) -> int:
+    def estimate_tokens_in_prompt(self, prompt: LmPrompt[T]) -> int:
         raise NotImplementedError
 
     @property
     def token_limit(self):
         raise NotImplementedError
 
-    def could_completion_go_over_token_limit(self, prompt: LmPrompt) -> bool:
+    def could_completion_go_over_token_limit(self, prompt: LmPrompt[T]) -> bool:
         count = self.estimate_tokens_in_prompt(prompt)
         return (
             count + (prompt.max_tokens or self.default_tokens_generated)
@@ -255,10 +256,12 @@ def supports_prefilled_chat(self) -> bool:
 
 
 def get_mock_predictor(
-    predict_func: Callable[[LmPrompt], LmPrediction] = None,
+    predict_func: Callable[[LmPrompt[T]], LmPrediction[T]] = None,
     is_chat_model: bool = False,
 ):
     """Gets a mock predictor. By default returns whatever the prompt txt is"""
+    
+    S = TypeVar('S')  # Local TypeVar for the mock predictor
 
     class MockPredict(LmPredictor):
         def get_model_cache_key(self):
@@ -268,7 +271,7 @@ def get_model_cache_key(self):
         def is_chat_model(self) -> bool:
             return is_chat_model
 
-        def _predict_maybe_cached(self, prompt):
+        def _predict_maybe_cached(self, prompt: LmPrompt[S]) -> LmPrediction[S]:
             if predict_func is None:
                 return LmPrediction(
                     prompt.get_text_as_string_default_form(),
diff --git a/lmwrapper/structs.py b/lmwrapper/structs.py
index cd193e6..282100c 100644
--- a/lmwrapper/structs.py
+++ b/lmwrapper/structs.py
@@ -1,13 +1,17 @@
 import contextlib
 import dataclasses
+import json
 import pickle
 import statistics
 from dataclasses import dataclass, field
-from typing import Any, Optional, Union
+from typing import Any, Generic, Optional, TypeVar, Union
 
 from lmwrapper.internals import ModelInternalsResults
 from lmwrapper.utils import StrEnum
 
+# Define TypeVar for user metadata
+T = TypeVar('T')
+
 LM_CHAT_DIALOG_COERCIBLE_TYPES = Union[
     str,
     list[Union["LmChatTurn", tuple[str, str], dict, str]],
@@ -34,7 +38,7 @@ class StopMode(StrEnum):
 
 
 @dataclass(frozen=True)
-class LmPrompt:
+class LmPrompt(Generic[T]):
     text: str | LM_CHAT_DIALOG_COERCIBLE_TYPES
     """The actual text of the prompt. If it is a LM_CHAT_DIALOG_COERCIBLE_TYPES
     which can become a LmChatDialog (such as a list of strings) it will be converted
@@ -125,6 +129,11 @@ class LmPrompt:
     """Whether or not to add special tokens when encoding the prompt."""
     model_internals_request: Optional["ModelInternalsRequest"] = None
     """Used to attempt to get hidden states and attentions from the model."""
+    metadata: Optional[T] = None
+    """Optional user-defined metadata that gets transferred to the resulting LmPrediction.
+    This is not used for caching and can be any type. It's useful for tracking
+    additional information with each prompt and prediction (e.g., ground truth labels,
+    problem identifiers)."""
 
     # TODO: make a auto_reduce_max_tokens to reduce when might go over.
 
@@ -208,11 +217,15 @@ def get_text_as_string_default_form(self) -> str:
         else:
             return self.text
 
-    def dict_serialize(self) -> dict:
+    def dict_serialize(self, include_metadata: bool = False) -> dict:
         """
         Serialize the prompt into a json-compatible dictionary. Note this is not
         guaranteed to be the same as the JSON representation for use
         in an openai api call. This is just for serialization purposes.
+        
+        Args:
+            include_metadata: Whether to include metadata in serialization.
+                Default is False since metadata should not be part of the cache key.
         """
         out = {
             "max_tokens": self.max_tokens,
@@ -232,6 +245,16 @@ def dict_serialize(self) -> dict:
             out["text"] = self.get_text_as_chat().as_dicts()
         else:
             out["text"] = self.text
+            
+        if include_metadata and self.metadata is not None:
+            try:
+                # Test if it's JSON serializable
+                json.dumps(self.metadata)
+                out["metadata"] = self.metadata
+            except (TypeError, ValueError):
+                # If metadata isn't JSON serializable, leave it out
+                pass
+                
         return out
 
 
@@ -316,10 +339,10 @@ def to_default_string_prompt(self) -> str:
 
 
 @dataclass
-class LmPrediction:
+class LmPrediction(Generic[T]):
     completion_text: str | None
     """The new text generated. It might be None if errors"""
-    prompt: LmPrompt
+    prompt: LmPrompt[T]
     metad: Any
     internals: ModelInternalsResults | None = field(default=None, kw_only=True)
     error_message: str | None = field(default=None, kw_only=True)
@@ -458,10 +481,11 @@ def dict_serialize(
         self,
         pull_out_props: bool = True,
         include_metad: bool = False,
+        include_metadata: bool = False,
     ) -> dict[str, Any]:
         out = {
             "completion_text": self.completion_text,
-            "prompt": self.prompt.dict_serialize(),
+            "prompt": self.prompt.dict_serialize(include_metadata=include_metadata),
             "was_cached": self.was_cached,
             "error_message": self.error_message,
         }
diff --git a/pyproject.toml b/pyproject.toml
index db81f3e..9d710a3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,7 +25,7 @@ include = ["lmwrapper*"]
 
 [project]
 name = "lmwrapper"
-version = "0.16.3.0"
+version = "0.16.4.0"
 authors = [
     { name = "David Gros" },
     { name = "Claudio Spiess" },
diff --git a/test/test_models_common.py b/test/test_models_common.py
index ea6f759..1b982cc 100644
--- a/test/test_models_common.py
+++ b/test/test_models_common.py
@@ -8,6 +8,7 @@
 import numpy as np
 import pytest
 
+from lmwrapper.abstract_predictor import LmPredictor
 from lmwrapper.batch_config import CompletionWindow
 from lmwrapper.caching import cache_dir, clear_cache_dir
 from lmwrapper.huggingface_wrapper import get_huggingface_lm
@@ -1107,6 +1108,87 @@ def test_system_prompt(lm):
     assert pred.completion_text.strip() == "PARIS"
 
 
+@pytest.mark.parametrize("lm", ALL_MODELS, ids=get_model_name)
+def test_metadata_predict(lm):
+    # Test with string metadata
+    prompt = LmPrompt(
+        "Count from 1 to 5:",
+        max_tokens=10,
+        cache=False,
+        temperature=0,
+        metadata="test_metadata_string"
+    )
+    pred = lm.predict(prompt)
+    assert pred.prompt.metadata == "test_metadata_string"
+    
+    # Test with dictionary metadata
+    metadata_dict = {"label": "counting", "id": 12345}
+    prompt = LmPrompt(
+        "Count from 1 to 5:",
+        max_tokens=10,
+        cache=False,
+        temperature=0,
+        metadata=metadata_dict
+    )
+    pred = lm.predict(prompt)
+    assert pred.prompt.metadata == metadata_dict
+    assert pred.prompt.metadata["label"] == "counting"
+    assert pred.prompt.metadata["id"] == 12345
+
+
+@pytest.mark.parametrize("lm", ALL_MODELS, ids=get_model_name)
+def test_metadata_predict_many(lm):
+    # Create prompts with different metadata
+    prompts = [
+        LmPrompt(
+            f"What is {i} + {i}?",
+            max_tokens=5,
+            cache=False,
+            temperature=0,
+            metadata={"question_id": i, "expected_answer": i*2}
+        )
+        for i in range(1, 4)
+    ]
+    
+    # Use predict_many and verify metadata is preserved
+    results = list(lm.predict_many(prompts, CompletionWindow.ASAP))
+    
+    for i, result in enumerate(results):
+        expected_id = i + 1
+        expected_answer = expected_id * 2
+        assert result.prompt.metadata["question_id"] == expected_id
+        assert result.prompt.metadata["expected_answer"] == expected_answer
+
+
+@pytest.mark.parametrize("lm", ALL_MODELS, ids=get_model_name)
+def test_metadata_with_cache_hit(lm: LmPredictor):
+    """Test that metadata is preserved when there's a cache hit."""
+    # First prompt with metadata to populate the cache
+    prompt1 = LmPrompt(
+        "What is 5 + 5?",
+        max_tokens=5,
+        cache=True,
+        temperature=0,
+        metadata={"original": True, "id": 1}
+    )
+    result1 = lm.predict(prompt1)
+    
+    # Same prompt with different metadata should use cache but keep the new metadata
+    prompt2 = LmPrompt(
+        "What is 5 + 5?",
+        max_tokens=5,
+        cache=True,
+        temperature=0,
+        metadata={"original": False, "id": 2}
+    )
+    result2 = lm.predict(prompt2)
+    
+    # Check that the result is from cache but has the new metadata
+    assert result2.was_cached
+    assert result2.prompt.metadata["original"] == False
+    assert result2.prompt.metadata["id"] == 2
+
+
 @pytest.mark.parametrize(
     "lm", CHAT_MODELS,
     ids=get_model_name