diff --git a/packages/overture-schema-codegen/changelog.d/674.feature.md b/packages/overture-schema-codegen/changelog.d/674.feature.md
new file mode 100644
index 000000000..7076fa8b1
--- /dev/null
+++ b/packages/overture-schema-codegen/changelog.d/674.feature.md
@@ -0,0 +1 @@
+Documented deprecation in the generated Markdown reference: a field marked `Field(deprecated=...)` gets a note in its description and a `(deprecated)` type qualifier, and a model marked `@deprecated(...)` gets a warning admonition on its feature page.
diff --git a/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/model_extraction.py b/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/model_extraction.py
index 7371db208..620c01ec1 100644
--- a/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/model_extraction.py
+++ b/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/model_extraction.py
@@ -46,6 +46,39 @@ def resolve_field_alias(field_name: str, field_info: FieldInfo) -> str:
     return field_name
 
 
+def _field_deprecation(field_info: FieldInfo) -> tuple[bool, str | None]:
+    """Return `(is_deprecated, message)` from Pydantic's `deprecated`.
+
+    Pydantic admits three forms on `field_info.deprecated`: a bare `True`, a
+    string message, or a [PEP 702](https://peps.python.org/pep-0702/)
+    `deprecated(...)` marker (`warnings.deprecated` /
+    `typing_extensions.deprecated`) -- usable directly as `Annotated` metadata
+    as well as inside `Field(deprecated=...)`. All three mean deprecated; the
+    string and the marker also carry prose, the marker's on its `.message`.
+    """
+    deprecated = field_info.deprecated
+    if deprecated is None or deprecated is False:
+        return False, None
+    if isinstance(deprecated, str):
+        return True, deprecated
+    message = getattr(deprecated, "message", None)
+    return True, message if isinstance(message, str) else None
+
+
+def _model_deprecation(model_class: type[BaseModel]) -> str | None:
+    """Return the class's own `@deprecated` message, or None.
+
+    [PEP 702](https://peps.python.org/pep-0702/)'s `@deprecated("message")`
+    sets `__deprecated__` on the decorated class, and `message` is a required
+    argument, so there is no bare-flag form to normalize. Read from
+    `__dict__` rather than with `getattr`: attribute lookup walks the MRO, so
+    a subclass of a deprecated model would report its parent's message and
+    render a deprecation it never declared.
+    """
+    deprecated = model_class.__dict__.get("__deprecated__")
+    return deprecated if isinstance(deprecated, str) else None
+
+
 def _is_field_required(field_info: FieldInfo, is_optional: bool) -> bool:
     """Determine whether a field is required (no default and not Optional)."""
     has_default = (
@@ -154,6 +187,7 @@ def _extract_model_recursive(
         entry_point=entry_point,
         partitions=partitions,
         constraints=ModelConstraint.get_model_constraints(model_class),
+        deprecated=_model_deprecation(model_class),
     )
     cache[model_class] = spec
     descendant_ancestors = ancestors | {model_class}
@@ -178,6 +212,7 @@ def _extract_model_recursive(
         # misses those constraints. Reattach them at the topmost
         # constraint-bearing layer.
         shape = attach_field_metadata(shape, field_info)
+        is_deprecated, deprecation_message = _field_deprecation(field_info)
         fields.append(
             FieldSpec(
                 name=resolve_field_alias(field_name, field_info),
@@ -185,6 +220,8 @@ def _extract_model_recursive(
                 description=field_info.description or ti_description,
                 is_required=_is_field_required(field_info, is_optional),
                 is_optional=is_optional,
+                is_deprecated=is_deprecated,
+                deprecation_message=deprecation_message,
             )
         )
 
diff --git a/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/specs.py b/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/specs.py
index 6b5259da1..47e03e2af 100644
--- a/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/specs.py
+++ b/packages/overture-schema-codegen/src/overture/schema/codegen/extraction/specs.py
@@ -134,6 +134,11 @@ class FieldSpec:
     description: str | None = None
     is_required: bool = True
     is_optional: bool = False
+    # Pydantic's `deprecated`, normalized. The flag and the message are
+    # separate because `Field(deprecated=True)` is deprecated with no prose,
+    # which a lone `str | None` can express only as a sentinel string.
+    is_deprecated: bool = False
+    deprecation_message: str | None = None
 
 
 @dataclass
@@ -147,6 +152,9 @@ class RecordSpec(_SourceTypeIdentityMixin):
     entry_point: str | None = None
     partitions: Mapping[str, str] = field(default_factory=dict)
     constraints: tuple[ModelConstraint, ...] = ()
+    # The class's own `@deprecated` message. A single `str | None` suffices
+    # here, unlike on `FieldSpec`: the decorator's `message` is required.
+    deprecated: str | None = None
 
 
 @dataclass
diff --git a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/renderer.py b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/renderer.py
index 8f0911ab8..83ce28d8c 100644
--- a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/renderer.py
+++ b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/renderer.py
@@ -200,6 +200,20 @@ def _format_example_value(value: object) -> str:
     return f"`{_truncate(str(value))}`"
 
 
+_GENERIC_FIELD_DEPRECATION_MESSAGE = "This field is deprecated."
+
+
+def _field_deprecation_note(field: FieldSpec) -> str:
+    """Render a field's deprecation as a note for the constraint appender.
+
+    A bare `deprecated=True` carries no prose of its own, so the generic
+    message stands in rather than letting a message-less flag render as
+    nothing at all.
+    """
+    message = field.deprecation_message or _GENERIC_FIELD_DEPRECATION_MESSAGE
+    return f"**Deprecated:** {message}"
+
+
 def _field_template_context(
     field: FieldSpec,
     ctx: LinkContext | None = None,
@@ -208,11 +222,17 @@ def _field_template_context(
     description = (
         _sanitize_for_table_cell(field.description) if field.description else None
     )
-    return _FieldRow(
+    row = _FieldRow(
         name=field.name,
         type_str=format_type(field, ctx),
         description=description,
     )
+    if field.is_deprecated:
+        # Through the same appender constraint notes use: a deprecation note
+        # is one more thing said about the field, not a separate rendering
+        # mechanism.
+        _annotate_constraint_notes(row, [_field_deprecation_note(field)])
+    return row
 
 
 def _annotate_constraint_notes(
diff --git a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/templates/feature.md.jinja2 b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/templates/feature.md.jinja2
index 78a183c5e..25011b21b 100644
--- a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/templates/feature.md.jinja2
+++ b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/templates/feature.md.jinja2
@@ -1,4 +1,12 @@
 # {{ model.name }}
+{% if model.deprecated %}
+
+:::warning[Deprecated]
+
+{{ model.deprecated }}
+
+:::
+{% endif %}
 {% if model.description %}
 
 {{ model.description | linkify_urls }}
diff --git a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/type_format.py b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/type_format.py
index da72e186b..6f797549d 100644
--- a/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/type_format.py
+++ b/packages/overture-schema-codegen/src/overture/schema/codegen/markdown/type_format.py
@@ -280,6 +280,8 @@ def format_type(field: FieldSpec, ctx: LinkContext | None = None) -> str:
     display = _format_shape(field.shape, ctx, qualifiers)
     if not field.is_required:
         qualifiers.append("optional")
+    if field.is_deprecated:
+        qualifiers.append("deprecated")
     if qualifiers:
         return f"{display} ({', '.join(qualifiers)})"
     return display
diff --git a/packages/overture-schema-codegen/tests/test_markdown_renderer.py b/packages/overture-schema-codegen/tests/test_markdown_renderer.py
index 3c929f289..7e74071ec 100644
--- a/packages/overture-schema-codegen/tests/test_markdown_renderer.py
+++ b/packages/overture-schema-codegen/tests/test_markdown_renderer.py
@@ -25,6 +25,7 @@
     spec_for_model,
 )
 from pydantic import BaseModel, Field
+from typing_extensions import deprecated
 
 from overture.schema.codegen.extraction.examples import ExampleRecord
 from overture.schema.codegen.extraction.model_extraction import extract_model
@@ -1479,3 +1480,100 @@ def test_used_by_section(self) -> None:
         result = render_pydantic_type(HTTP_URL_SPEC, link_ctx=ctx, used_by=used_by)
         assert "## Used By" in result
         assert "Place" in result
+
+
+class TestRenderFeatureDeprecation:
+    """Tests for deprecation rendering (OvertureMaps/schema#674).
+
+    One deprecated field and one deprecated model, defined locally so
+    neither reaches the published schema -- the fixture the issue asks
+    for. Each positive assertion is paired with a control on an
+    undeprecated sibling field/model, per the issue's fourth acceptance
+    criterion: nothing changes for the un-deprecated case.
+    """
+
+    def test_field_with_deprecation_message_renders_note_and_tag(self) -> None:
+        """A `Field(deprecated="...")` field gets the note and the `(deprecated)` tag."""
+
+        class ModelWithDeprecatedField(BaseModel):
+            """Model with one deprecated field and one current field."""
+
+            old_field: str | None = Field(
+                default=None,
+                deprecated="Use `new_field` instead. Deprecated in v1.18.0.",
+            )
+            new_field: str | None = Field(default=None, description="The replacement.")
+
+        spec = extract_model(ModelWithDeprecatedField)
+        result = render_model(spec)
+
+        lines = result.splitlines()
+        old_line = next(line for line in lines if "| `old_field` |" in line)
+        new_line = next(line for line in lines if "| `new_field` |" in line)
+
+        assert "(optional, deprecated)" in old_line
+        assert (
+            "**Deprecated:** Use `new_field` instead. Deprecated in v1.18.0."
+            in old_line
+        )
+        # Control: the current field gets neither the tag nor a note.
+        assert "deprecated" not in new_line
+        assert "Deprecated" not in new_line
+
+    def test_bare_deprecated_true_renders_generic_message(self) -> None:
+        """`deprecated=True` with no message still renders a note, not silence."""
+
+        class ModelWithBareDeprecation(BaseModel):
+            """Model with a bare-flagged deprecated field."""
+
+            old_field: str | None = Field(default=None, deprecated=True)
+
+        spec = extract_model(ModelWithBareDeprecation)
+        result = render_model(spec)
+
+        lines = result.splitlines()
+        old_line = next(line for line in lines if "| `old_field` |" in line)
+
+        assert "(optional, deprecated)" in old_line
+        assert "**Deprecated:** This field is deprecated." in old_line
+
+    def test_deprecated_model_renders_banner(self) -> None:
+        """A `@deprecated(...)`-decorated model renders a banner at the page top.
+
+        Docusaurus renders the generated reference, so the banner is an
+        admonition. Blank lines inside the directive keep Prettier from
+        collapsing it into invalid syntax.
+        """
+
+        @deprecated("Use `NewFeature` instead. Deprecated in v1.18.0.")
+        class OldFeature(BaseModel):
+            """An old feature, kept only to be deprecated."""
+
+            name: str
+
+        spec = extract_model(OldFeature)
+        result = render_model(spec)
+
+        assert (
+            ":::warning[Deprecated]\n\n"
+            "Use `NewFeature` instead. Deprecated in v1.18.0.\n\n"
+            ":::" in result
+        )
+        # The banner precedes the docstring description.
+        banner_idx = result.index(":::warning[Deprecated]")
+        description_idx = result.index("An old feature, kept only to be deprecated.")
+        assert banner_idx < description_idx
+
+    def test_current_model_renders_no_banner(self) -> None:
+        """The control: an undeprecated model gets no banner at all."""
+
+        class CurrentFeature(BaseModel):
+            """A current feature."""
+
+            name: str
+
+        spec = extract_model(CurrentFeature)
+        result = render_model(spec)
+
+        assert ":::warning[Deprecated]" not in result
+        assert "Deprecated" not in result
diff --git a/packages/overture-schema-codegen/tests/test_model_extraction.py b/packages/overture-schema-codegen/tests/test_model_extraction.py
index e8b3fd2c7..2e5b0251f 100644
--- a/packages/overture-schema-codegen/tests/test_model_extraction.py
+++ b/packages/overture-schema-codegen/tests/test_model_extraction.py
@@ -2,8 +2,10 @@
 
 from typing import Annotated, Optional
 
+import pytest
 from codegen_test_support import FeatureWithRootModel
 from pydantic import BaseModel, Field
+from typing_extensions import deprecated
 
 from overture.schema.codegen.extraction.field import (
     ArrayOf,
@@ -179,3 +181,125 @@ class M(BaseModel):
     assert isinstance(items_field.shape, ArrayOf)
     constraints = [cs.constraint for cs in items_field.shape.constraints]
     assert ArrayMinLen(min_length=2) in constraints
+
+
+def test_field_deprecated_with_message_carries_flag_and_message() -> None:
+    """`Field(deprecated="...")` sets both `is_deprecated` and the message."""
+
+    class M(BaseModel):
+        old: str | None = Field(default=None, deprecated="Use `new` instead.")
+
+    spec = extract_model(M)
+    old = next(f for f in spec.fields if f.name == "old")
+
+    assert old.is_deprecated is True
+    assert old.deprecation_message == "Use `new` instead."
+
+
+def test_field_deprecated_bare_true_carries_flag_with_no_message() -> None:
+    """A bare `deprecated=True` sets the flag but leaves the message `None`.
+
+    The control on the message test above: without this, a field that
+    declares no message at all could not be told apart from one that does.
+    """
+
+    class M(BaseModel):
+        old: str | None = Field(default=None, deprecated=True)
+
+    spec = extract_model(M)
+    old = next(f for f in spec.fields if f.name == "old")
+
+    assert old.is_deprecated is True
+    assert old.deprecation_message is None
+
+
+def test_field_deprecated_via_annotated_marker_carries_the_message() -> None:
+    """The PEP 702 marker used directly as `Annotated` metadata also carries.
+
+    `deprecated(...)` is usable both inside `Field(deprecated=...)` and
+    directly as `Annotated` metadata; Pydantic surfaces the marker object
+    itself (not a plain string) on `field_info.deprecated` for this form, so
+    its `.message` has to be unwrapped rather than read as a string.
+    """
+
+    class M(BaseModel):
+        old: Annotated[str, deprecated("Use `new` instead.")] = "x"
+
+    spec = extract_model(M)
+    old = next(f for f in spec.fields if f.name == "old")
+
+    assert old.is_deprecated is True
+    assert old.deprecation_message == "Use `new` instead."
+
+
+def test_field_not_deprecated_by_default() -> None:
+    """A field that never declares `deprecated` extracts as not deprecated.
+
+    A stray `is_deprecated=True` default on `FieldSpec` would satisfy the
+    two tests above; this one would fail.
+    """
+
+    class M(BaseModel):
+        current: str = "x"
+
+    spec = extract_model(M)
+    current = next(f for f in spec.fields if f.name == "current")
+
+    assert current.is_deprecated is False
+    assert current.deprecation_message is None
+
+
+def test_model_deprecated_via_pep_702_carries_the_message() -> None:
+    """A class decorated with `@deprecated(...)` carries its message on the spec.
+
+    `typing_extensions.deprecated` (PEP 702) sets `__deprecated__` on the
+    decorated class.
+    """
+
+    @deprecated("Use `NewFeature` instead.")
+    class OldFeature(BaseModel):
+        name: str
+
+    spec = extract_model(OldFeature)
+
+    assert spec.deprecated == "Use `NewFeature` instead."
+
+
+def test_model_deprecation_does_not_inherit_to_subclasses() -> None:
+    """A subclass of a deprecated model is not itself deprecated.
+
+    `__deprecated__` is a plain class attribute, so ordinary attribute
+    lookup finds it through the MRO. Reading it that way would mark every
+    subclass of a deprecated model deprecated and render a banner on a
+    feature page that never declared one. `TransportationSegment` and
+    `VehicleSelectorBase` both have subclasses in the published schema.
+    """
+
+    @deprecated("Use `NewFeature` instead.")
+    class OldFeature(BaseModel):
+        name: str
+
+    # Subclassing a deprecated class is itself what PEP 702 warns about.
+    with pytest.warns(DeprecationWarning):
+
+        class CurrentFeature(OldFeature):
+            pass
+
+    assert getattr(CurrentFeature, "__deprecated__", None) is not None
+    assert extract_model(CurrentFeature).deprecated is None
+    assert extract_model(OldFeature).deprecated == "Use `NewFeature` instead."
+
+
+def test_model_not_deprecated_by_default() -> None:
+    """A model with no `@deprecated` decorator extracts with `deprecated=None`.
+
+    The control on the test above: without it, a stray non-`None` default
+    on `RecordSpec.deprecated` would satisfy it trivially.
+    """
+
+    class CurrentFeature(BaseModel):
+        name: str
+
+    spec = extract_model(CurrentFeature)
+
+    assert spec.deprecated is None