diff --git a/src/ocrmypdf/_plugin_registry.py b/src/ocrmypdf/_plugin_registry.py
new file mode 100644
index 00000000..506efc75
--- /dev/null
+++ b/src/ocrmypdf/_plugin_registry.py
@@ -0,0 +1,73 @@
+# SPDX-FileCopyrightText: 2024 James R. Barlow
+# SPDX-License-Identifier: MPL-2.0
+
+"""Plugin option registry for dynamic model composition."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any, Dict, Type
+
+from pydantic import BaseModel, create_model
+
+log = logging.getLogger(__name__)
+
+
+class PluginOptionRegistry:
+    """Registry for plugin option models."""
+    
+    def __init__(self):
+        self._option_models: Dict[str, Type[BaseModel]] = {}
+        self._extended_model_cache: Type[BaseModel] | None = None
+    
+    def register_option_model(self, namespace: str, model_class: Type[BaseModel]) -> None:
+        """Register a plugin's option model.
+        
+        Args:
+            namespace: The namespace for the plugin options (e.g., 'tesseract')
+            model_class: The Pydantic model class for the plugin options
+        """
+        if namespace in self._option_models:
+            log.warning(f"Plugin option namespace '{namespace}' already registered, overriding")
+        
+        self._option_models[namespace] = model_class
+        # Clear cache when new models are registered
+        self._extended_model_cache = None
+        
+        log.debug(f"Registered plugin option model for namespace '{namespace}': {model_class.__name__}")
+    
+    def get_registered_models(self) -> Dict[str, Type[BaseModel]]:
+        """Get all registered plugin option models."""
+        return self._option_models.copy()
+    
+    def get_extended_options_model(self, base_model: Type[BaseModel]) -> Type[BaseModel]:
+        """Create an extended options model that includes all registered plugin options.
+        
+        Args:
+            base_model: The base OCROptions model to extend
+            
+        Returns:
+            A new model class that includes the base model fields plus all plugin option fields
+        """
+        if self._extended_model_cache is not None:
+            return self._extended_model_cache
+        
+        # Start with base model fields
+        model_fields = {}
+        
+        # Add plugin option models as nested fields
+        for namespace, model_class in self._option_models.items():
+            model_fields[namespace] = (model_class, model_class())
+        
+        # Create the extended model
+        self._extended_model_cache = create_model(
+            'ExtendedOCROptions',
+            __base__=base_model,
+            **model_fields
+        )
+        
+        return self._extended_model_cache
+    
+    def clear_cache(self) -> None:
+        """Clear the extended model cache."""
+        self._extended_model_cache = None
diff --git a/src/ocrmypdf/api.py b/src/ocrmypdf/api.py
index 16978899..d8f92b00 100644
--- a/src/ocrmypdf/api.py
+++ b/src/ocrmypdf/api.py
@@ -79,7 +79,7 @@ def setup_plugin_infrastructure(
     This function handles:
     1. Creating or validating the plugin manager
     2. Calling plugin initialization hooks
-    3. Setting up any future plugin registries (Phase 2)
+    3. Setting up plugin option registry
     
     Args:
         plugins: List of plugin paths/names to load
@@ -105,10 +105,22 @@ def setup_plugin_infrastructure(
     if not plugin_manager:
         plugin_manager = get_plugin_manager(plugins)
     
-    # Initialize plugins (this was missing in the API path)
+    # Initialize plugins
     plugin_manager.hook.initialize(plugin_manager=plugin_manager)  # pylint: disable=no-member
     
-    # Future: Initialize plugin option registry here (Phase 2)
+    # Initialize plugin option registry
+    from ocrmypdf._plugin_registry import PluginOptionRegistry
+    registry = PluginOptionRegistry()
+    
+    # Let plugins register their option models
+    option_models = plugin_manager.hook.register_options()  # pylint: disable=no-member
+    for plugin_options in option_models:
+        if plugin_options:  # Skip None returns
+            for namespace, model_class in plugin_options.items():
+                registry.register_option_model(namespace, model_class)
+    
+    # Store registry in plugin manager for later access
+    plugin_manager._option_registry = registry
     
     return plugin_manager
 
diff --git a/src/ocrmypdf/builtin_plugins/ghostscript.py b/src/ocrmypdf/builtin_plugins/ghostscript.py
index 550ac599..b7a5e63b 100644
--- a/src/ocrmypdf/builtin_plugins/ghostscript.py
+++ b/src/ocrmypdf/builtin_plugins/ghostscript.py
@@ -29,6 +29,12 @@ class GhostscriptOptions(BaseModel):
     pdfa_image_compression: Annotated[str, Field(description="PDF/A image compression method")] = "auto"
 
 
+@hookimpl
+def register_options():
+    """Register Ghostscript option model."""
+    return {'ghostscript': GhostscriptOptions}
+
+
 @hookimpl
 def add_options(parser):
     gs = parser.add_argument_group("Ghostscript", "Advanced control of Ghostscript")
diff --git a/src/ocrmypdf/builtin_plugins/optimize.py b/src/ocrmypdf/builtin_plugins/optimize.py
index e5e3ffc6..23a25fb3 100644
--- a/src/ocrmypdf/builtin_plugins/optimize.py
+++ b/src/ocrmypdf/builtin_plugins/optimize.py
@@ -33,6 +33,12 @@ class OptimizeOptions(BaseModel):
     jbig2_threshold: Annotated[float, Field(ge=0.4, le=0.9, description="JBIG2 symbol classification threshold")] = 0.85
 
 
+@hookimpl
+def register_options():
+    """Register optimization option model."""
+    return {'optimize': OptimizeOptions}
+
+
 @hookimpl
 def add_options(parser):
     optimizing = parser.add_argument_group(
diff --git a/src/ocrmypdf/builtin_plugins/tesseract_ocr.py b/src/ocrmypdf/builtin_plugins/tesseract_ocr.py
index 1f8c94e4..dd10cbe7 100644
--- a/src/ocrmypdf/builtin_plugins/tesseract_ocr.py
+++ b/src/ocrmypdf/builtin_plugins/tesseract_ocr.py
@@ -38,6 +38,12 @@ class TesseractOptions(BaseModel):
     downsample_above: Annotated[int, Field(ge=100, le=32767, description="Downsample images larger than this pixel size")] = 32767
 
 
+@hookimpl
+def register_options():
+    """Register Tesseract option model."""
+    return {'tesseract': TesseractOptions}
+
+
 @hookimpl
 def add_options(parser):
     tess = parser.add_argument_group("Tesseract", "Advanced control of Tesseract OCR")
diff --git a/src/ocrmypdf/pluginspec.py b/src/ocrmypdf/pluginspec.py
index e456e957..01b26c20 100644
--- a/src/ocrmypdf/pluginspec.py
+++ b/src/ocrmypdf/pluginspec.py
@@ -13,6 +13,7 @@ from pathlib import Path
 from typing import TYPE_CHECKING, NamedTuple
 
 import pluggy
+from pydantic import BaseModel
 
 from ocrmypdf import Executor, PdfContext
 from ocrmypdf._options import OCROptions
@@ -87,6 +88,28 @@ def add_options(parser: ArgumentParser) -> None:
     """
 
 
+@hookspec
+def register_options() -> dict[str, type[BaseModel]]:
+    """Return plugin's option models keyed by namespace.
+    
+    This hook allows plugins to register their option models with the
+    plugin option registry. The returned dictionary should map namespace
+    strings to Pydantic model classes.
+    
+    Returns:
+        Dictionary mapping namespace strings to BaseModel classes
+        
+    Example:
+        @hookimpl
+        def register_options():
+            return {'tesseract': TesseractOptions}
+            
+    Note:
+        This hook will be called from the main process during plugin
+        infrastructure setup, before child worker processes are forked.
+    """
+
+
 @hookspec
 def check_options(options: OCROptions) -> None:
     """Called to ask the plugin to check all of the options.