diff --git a/fieldExtraction/crosswalk/README.md b/fieldExtraction/crosswalk/README.md
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+This framework allows flexible serialization and application of crosswalk tables.
+
+### Features
+- Create crosswalks from Excel files or dictionaries
+- Save crosswalks as JSON for easy reuse
+- Apply crosswalks with customizable default behavior
+- Metadata tracking for column mappings
+
+### Creating a Crosswalk
+```
+from crosswalk_utils import CrosswalkBuilder
+
+# From Excel
+builder = CrosswalkBuilder()
+builder.from_excel(
+    path="CROSSWALK_PROVIDER_TYPE.20220106.xlsx",
+    sheet_name='Prac',
+    from_col="Practitioner Specialty",
+    to_col="Taxonomy"
+).save('crosswalk_provider_type.json')
+
+# You can also create from a dictionary
+builder.from_dict(
+    mapping={'Acupuncturist': '171100000X'},
+    from_col='Specialty',
+    to_col='Taxonomy'
+)
+```
+
+### Applying a Crosswalk
+```
+import json
+from crosswalk_utils import apply_crosswalk
+
+# Load the mapping
+with open('crosswalk_provider_type.json') as f:
+    data = json.load(f)
+    
+# Apply the crosswalk
+result = apply_crosswalk(
+    val="Acupuncturist",
+    mapping=data['mapping'],
+    default=None  # Optional: specify default for unmapped values
+)
+# Result: '171100000X'
+```
diff --git a/fieldExtraction/crosswalk/crosswalk_utils.py b/fieldExtraction/crosswalk/crosswalk_utils.py
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+import json
+
+import pandas as pd
+
+
+class CrosswalkBuilder:
+    def __init__(self):
+        self.mapping: dict[str, str] = {}
+        self.metadata: dict[str, str | None] = {}
+
+    def from_excel(
+        self, path: str, from_col: str, to_col: str, sheet_name: str | None = None
+    ) -> "CrosswalkBuilder":
+        """Load mapping from an excel file
+
+        Args:
+            path (str): location for the excel file
+            from_col (str): Source column (for keys)
+            to_col (str): Destination column (for values)
+            sheet_name (str|None, optional): Sheet name in the excel file. Defaults to None.
+
+        Returns:
+            CrosswalkBuilder: the builder instance for method chaining
+        """
+        if sheet_name is None:
+            # If sheet_name is not provided, read the first sheet
+            df = pd.read_excel(path, sheet_name=0)
+        else:
+            df = pd.read_excel(path, sheet_name=sheet_name)
+
+        if from_col not in df.columns:
+            raise ValueError(f"Column '{from_col}' not found in the excel file")
+        elif to_col not in df.columns:
+            raise ValueError(f"Column '{to_col}' not found in the excel file")
+
+        self.metadata = {
+            "from_col": from_col,
+            "to_col": to_col,
+        }
+
+        self.mapping = dict(zip(df[from_col], df[to_col]))
+
+        return self
+
+    def from_dict(
+        self,
+        mapping: dict[str, str],
+        from_col: str | None = None,
+        to_col: str | None = None,
+    ) -> "CrosswalkBuilder":
+        """Load mapping from a dictionary
+
+        Args:
+            mapping (dict[str, str]): Mapping dictionary
+
+        Returns:
+            CrosswalkBuilder: the builder instance for method chaining
+        """
+        self.metadata = {
+            "from_col": from_col,
+            "to_col": to_col,
+        }
+        self.mapping = mapping
+        return self
+
+    def from_json(self, path: str) -> "CrosswalkBuilder":
+        """Load mapping from a JSON file
+
+        Args:
+            path (str): Path to the JSON file
+
+        Returns:
+            CrosswalkBuilder: the builder instance for method chaining
+        """
+        with open(path, "r") as f:
+            data = json.load(f)
+
+        self.metadata = data.get("metadata", {})
+        self.mapping = data.get("mapping", {})
+
+        return self
+
+    def save(self, output_path: str) -> None:
+        """Save the crosswalk to JSON.
+
+        Args:
+            output_path (str): Path to save the crosswalk
+        """
+        output_dict = {"metadata": self.metadata, "mapping": self.mapping}
+        with open(output_path, "w") as f:
+            json.dump(output_dict, f, indent=4)
+
+
+def apply_crosswalk(
+    val: str, mapping: dict[str, str], default: str | None = None
+) -> str:
+    """Apply a crosswalk to a value
+
+    Args:
+        val (str): Input value
+        mapping (dict[str, str]): Mapping dictionary
+        default (str | None, optional): Default value; if None and val is not found in the mapping, val is returned. Defaults to None.
+
+    Returns:
+        str: Crosswalked value
+    """
+    return mapping.get(val, default if default is not None else val)
diff --git a/fieldExtraction/crosswalk/test_crosswalk_utils.py b/fieldExtraction/crosswalk/test_crosswalk_utils.py
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+import json
+
+import pandas as pd
+import pytest
+
+from crosswalk_utils import CrosswalkBuilder, apply_crosswalk
+
+
+@pytest.fixture
+def sample_excel_file(tmp_path):
+    data = {"from_col": ["A", "B", "C"], "to_col": ["one", "two", "three"]}
+    df = pd.DataFrame(data)
+    file_path = tmp_path / "sample.xlsx"
+    df.to_excel(file_path, index=False)
+    return file_path
+
+
+@pytest.fixture
+def sample_json_file(tmp_path):
+    data = {
+        "metadata": {"from_col": "from_col", "to_col": "to_col"},
+        "mapping": {"A": "1", "B": "2", "C": "3"},
+    }
+    file_path = tmp_path / "sample.json"
+    with open(file_path, "w") as f:
+        json.dump(data, f)
+    return file_path
+
+
+def test_from_excel(sample_excel_file):
+    builder = CrosswalkBuilder()
+    builder.from_excel(sample_excel_file, "from_col", "to_col")
+    assert builder.mapping == {"A": "one", "B": "two", "C": "three"}
+    assert builder.metadata == {"from_col": "from_col", "to_col": "to_col"}
+
+
+def test_from_excel_missing_column(sample_excel_file):
+    builder = CrosswalkBuilder()
+    with pytest.raises(ValueError, match="Column 'nonexistent' not found"):
+        builder.from_excel(sample_excel_file, "nonexistent", "to_col")
+
+
+def test_from_dict():
+    mapping = {"A": "1", "B": "2", "C": "3"}
+    builder = CrosswalkBuilder()
+    builder.from_dict(mapping)
+    assert builder.mapping == mapping
+    assert builder.metadata == {"from_col": None, "to_col": None}
+
+
+def test_from_json(sample_json_file):
+    builder = CrosswalkBuilder()
+    builder.from_json(sample_json_file)
+    assert builder.mapping == {"A": "1", "B": "2", "C": "3"}
+    assert builder.metadata == {"from_col": "from_col", "to_col": "to_col"}
+
+
+def test_json_roundtrip(tmp_path):
+    # Create and save a crosswalk
+    original = CrosswalkBuilder()
+    original.from_dict({"A": "1"}, "source", "target")
+    json_path = tmp_path / "test.json"
+    original.save(json_path)
+
+    # Load it back
+    loaded = CrosswalkBuilder().from_json(json_path)
+
+    # Check everything matches
+    assert loaded.mapping == original.mapping
+    assert loaded.metadata == original.metadata
+
+
+def test_save(tmp_path):
+    mapping = {"A": "1", "B": "2", "C": "3"}
+    builder = CrosswalkBuilder()
+    builder.from_dict(mapping, "from_col", "to_col")
+    output_path = tmp_path / "output.json"
+    builder.save(output_path)
+
+    with open(output_path, "r") as f:
+        data = json.load(f)
+
+    assert data["mapping"] == mapping
+    assert data["metadata"] == {"from_col": "from_col", "to_col": "to_col"}
+
+
+def test_apply_crosswalk():
+    mapping = {"A": "1", "B": "2", "C": "3"}
+    assert apply_crosswalk("A", mapping) == "1"
+    assert apply_crosswalk("D", mapping) == "D"
+    assert apply_crosswalk("D", mapping, default="0") == "0"