diff --git a/setup.cfg b/setup.cfg
index 40d7452..db95c83 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -22,7 +22,7 @@ classifiers =
     Programming Language :: Python :: 3.9
 
 [options]
-python_requires = >=3.8
+python_requires = >=3.8,<3.10
 package_dir =
     =src
 packages = find_namespace:
diff --git a/src/stactools/naip/grid.py b/src/stactools/naip/grid.py
new file mode 100644
index 0000000..13bd556
--- /dev/null
+++ b/src/stactools/naip/grid.py
@@ -0,0 +1,107 @@
+"""Implements the :stac-ext:`Grid Extension <grid>`."""
+
+import re
+from typing import Any, Dict, Optional, Pattern, Set, Union, cast
+
+import pystac
+from pystac.extensions.base import ExtensionManagementMixin, PropertiesExtension
+from pystac.extensions.hooks import ExtensionHooks
+
+SCHEMA_URI: str = "https://stac-extensions.github.io/grid/v1.0.0/schema.json"
+PREFIX: str = "grid:"
+
+# Field names
+CODE_PROP: str = PREFIX + "code"  # required
+
+CODE_REGEX: str = r"[A-Z]+-[-_.A-Za-z0-9]+"
+CODE_PATTERN: Pattern[str] = re.compile(CODE_REGEX)
+
+
+def validated_code(v: str) -> str:
+    if not isinstance(v, str):
+        raise ValueError("Invalid Grid code: must be str")
+    if not CODE_PATTERN.fullmatch(v):
+        raise ValueError(
+            f"Invalid Grid code: {v}" f" does not match the regex {CODE_REGEX}"
+        )
+    return v
+
+
+class GridExtension(
+    PropertiesExtension,
+    ExtensionManagementMixin[Union[pystac.Item, pystac.Collection]],
+):
+    """A concrete implementation of :class:`GridExtension` on an :class:`~pystac.Item`
+    that extends the properties of the Item to include properties defined in the
+    :stac-ext:`Grid Extension <grid>`.
+
+    This class should generally not be instantiated directly. Instead, call
+    :meth:`GridExtension.ext` on an :class:`~pystac.Item` to extend it.
+
+    .. code-block:: python
+
+       >>> item: pystac.Item = ...
+       >>> proj_ext = GridExtension.ext(item)
+    """
+
+    item: pystac.Item
+    """The :class:`~pystac.Item` being extended."""
+
+    properties: Dict[str, Any]
+    """The :class:`~pystac.Item` properties, including extension properties."""
+
+    def __init__(self, item: pystac.Item):
+        self.item = item
+        self.properties = item.properties
+
+    def __repr__(self) -> str:
+        return "<ItemGridExtension Item id={}>".format(self.item.id)
+
+    def apply(self, code: str) -> None:
+        """Applies Grid extension properties to the extended Item.
+
+        Args:
+            code : REQUIRED. The code of the Item's grid location.
+        """
+        self.code = validated_code(code)
+
+    @property
+    def code(self) -> Optional[str]:
+        """Get or sets the latitude band of the datasource."""
+        return self._get_property(CODE_PROP, str)
+
+    @code.setter
+    def code(self, v: str) -> None:
+        self._set_property(CODE_PROP, validated_code(v), pop_if_none=False)
+
+    @classmethod
+    def get_schema_uri(cls) -> str:
+        return SCHEMA_URI
+
+    @classmethod
+    def ext(cls, obj: pystac.Item, add_if_missing: bool = False) -> "GridExtension":
+        """Extends the given STAC Object with properties from the :stac-ext:`Grid
+        Extension <grid>`.
+
+        This extension can be applied to instances of :class:`~pystac.Item`.
+
+        Raises:
+
+            pystac.ExtensionTypeError : If an invalid object type is passed.
+        """
+        if isinstance(obj, pystac.Item):
+            cls.validate_has_extension(obj, add_if_missing)
+            return cast(GridExtension, GridExtension(obj))
+        else:
+            raise pystac.ExtensionTypeError(
+                f"Grid Extension does not apply to type '{type(obj).__name__}'"
+            )
+
+
+class GridExtensionHooks(ExtensionHooks):
+    schema_uri: str = SCHEMA_URI
+    prev_extension_ids: Set[str] = set()
+    stac_object_types = {pystac.STACObjectType.ITEM}
+
+
+Grid_EXTENSION_HOOKS: ExtensionHooks = GridExtensionHooks()
diff --git a/src/stactools/naip/stac.py b/src/stactools/naip/stac.py
index 383d47a..4661b2b 100644
--- a/src/stactools/naip/stac.py
+++ b/src/stactools/naip/stac.py
@@ -1,5 +1,6 @@
 import os
-from typing import List, Optional
+import re
+from typing import Final, List, Optional, Pattern
 
 import dateutil.parser
 import pystac
@@ -13,8 +14,11 @@
 from stactools.core.projection import reproject_geom
 
 from stactools.naip import constants
+from stactools.naip.grid import GridExtension
 from stactools.naip.utils import parse_fgdc_metadata
 
+DOQQ_PATTERN: Final[Pattern[str]] = re.compile(r"[A-Za-z]{2}_m_(\d{7})_(ne|se|nw|sw)_")
+
 
 def naip_item_id(state, resource_name):
     """Generates a STAC Item ID based on the state and the "Resource Description"
@@ -149,16 +153,21 @@ def create_item(
         item.common_metadata.providers.extend(additional_providers)
     item.common_metadata.gsd = gsd
 
-    # eo, for asset bands
+    # EO Extension, for asset bands
     EOExtension.add_to(item)
 
-    # proj
+    # Projection Extension
     projection = ProjectionExtension.ext(item, add_if_missing=True)
     projection.epsg = epsg
     projection.shape = image_shape
     projection.bbox = original_bbox
     projection.transform = transform
 
+    # Grid Extension
+    grid = GridExtension.ext(item, add_if_missing=True)
+    if match := DOQQ_PATTERN.search(item_id):
+        grid.code = f"DOQQ-{match.group(1)}{match.group(2).upper()}"
+
     # COG
     item.add_asset(
         "image",