diff --git a/include/sdf/Surface.hh b/include/sdf/Surface.hh
index b7ea1b802..e2d1d906a 100644
--- a/include/sdf/Surface.hh
+++ b/include/sdf/Surface.hh
@@ -17,6 +17,9 @@
 #ifndef SDF_SURFACE_HH_
 #define SDF_SURFACE_HH_
 
+#include <cstdint>
+#include <optional>
+
 #include <gz/math/Vector3.hh>
 #include <gz/utils/ImplPtr.hh>
 #include "sdf/Element.hh"
@@ -53,8 +56,17 @@ namespace sdf
     public: uint16_t CollideBitmask() const;
 
     /// \brief Set the collide bitmask parameter.
+    /// \param[in] _bitmask Category bitmask to set
     public: void SetCollideBitmask(const uint16_t _bitmask);
 
+    /// \brief Get the category bitmask parameter.
+    /// \return The category bitmask parameter.
+    public: std::optional<uint16_t> CategoryBitmask() const;
+
+    /// \brief Set the category bitmask parameter.
+    /// \param[in] _bitmask Category bitmask to set
+    public: void SetCategoryBitmask(const uint16_t _bitmask);
+
     /// \brief Private data pointer.
     GZ_UTILS_IMPL_PTR(dataPtr)
   };
diff --git a/python/src/sdf/pySurface.cc b/python/src/sdf/pySurface.cc
index ac296efea..efa1960bd 100644
--- a/python/src/sdf/pySurface.cc
+++ b/python/src/sdf/pySurface.cc
@@ -16,6 +16,7 @@
 #include "pySurface.hh"
 
 #include <pybind11/pybind11.h>
+#include <pybind11/stl.h>
 
 #include "sdf/Surface.hh"
 
@@ -37,6 +38,11 @@ void defineContact(pybind11::object module)
          "Get the collide bitmask parameter.")
     .def("set_collide_bitmask", &sdf::Contact::SetCollideBitmask,
          "Set the collide bitmask parameter.")
+    .def("category_bitmask", &sdf::Contact::CategoryBitmask,
+         "Get the category bitmask parameter.")
+    .def("set_category_bitmask", &sdf::Contact::SetCategoryBitmask,
+         "Set the category bitmask parameter.")
+
     .def("__copy__", [](const sdf::Contact &self) {
       return sdf::Contact(self);
     })
diff --git a/python/test/pySurface_TEST.py b/python/test/pySurface_TEST.py
index 998244e5f..70d539c34 100644
--- a/python/test/pySurface_TEST.py
+++ b/python/test/pySurface_TEST.py
@@ -24,6 +24,7 @@ class SurfaceTEST(unittest.TestCase):
   def test_default_construction(self):
       surface = Surface()
       self.assertEqual(surface.contact().collide_bitmask(), 0xFF)
+      self.assertFalse(surface.contact().category_bitmask())
 
 
   def test_assigment_construction(self):
@@ -54,11 +55,13 @@ def test_assigment_construction(self):
     friction.set_bullet_friction(bullet)
     friction.set_torsional(torsional)
     contact.set_collide_bitmask(0x12)
+    contact.set_category_bitmask(0x22)
     surface1.set_contact(contact)
     surface1.set_friction(friction)
 
     surface2 = surface1
     self.assertEqual(surface2.contact().collide_bitmask(), 0x12)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x22)
     self.assertEqual(surface2.friction().ode().mu(), 0.1)
     self.assertEqual(surface2.friction().ode().mu2(), 0.2)
     self.assertEqual(surface2.friction().ode().slip1(), 3)
@@ -78,9 +81,12 @@ def test_assigment_construction(self):
     self.assertEqual(surface2.friction().torsional().ode_slip(), 0.01)
 
     contact.set_collide_bitmask(0x21)
+    contact.set_category_bitmask(0x33)
     surface1.set_contact(contact)
     self.assertEqual(surface1.contact().collide_bitmask(), 0x21)
     self.assertEqual(surface2.contact().collide_bitmask(), 0x21)
+    self.assertEqual(surface1.contact().category_bitmask(), 0x33)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x33)
 
     ode.set_mu(1.1)
     ode.set_mu2(1.2)
@@ -165,11 +171,13 @@ def test_copy_construction(self):
     friction.set_bullet_friction(bullet)
     friction.set_torsional(torsional)
     contact.set_collide_bitmask(0x12)
+    contact.set_category_bitmask(0x22)
     surface1.set_contact(contact)
     surface1.set_friction(friction)
 
     surface2 = Surface(surface1)
     self.assertEqual(surface2.contact().collide_bitmask(), 0x12)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x22)
     self.assertEqual(surface2.friction().ode().mu(), 0.1)
     self.assertEqual(surface2.friction().ode().mu2(), 0.2)
     self.assertEqual(surface2.friction().ode().slip1(), 3)
@@ -189,9 +197,12 @@ def test_copy_construction(self):
     self.assertEqual(surface2.friction().torsional().ode_slip(), 0.01)
 
     contact.set_collide_bitmask(0x21)
+    contact.set_category_bitmask(0x33)
     surface1.set_contact(contact)
     self.assertEqual(surface1.contact().collide_bitmask(), 0x21)
     self.assertEqual(surface2.contact().collide_bitmask(), 0x12)
+    self.assertEqual(surface1.contact().category_bitmask(), 0x33)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x22)
 
     ode.set_mu(1.1)
     ode.set_mu2(1.2)
@@ -276,11 +287,13 @@ def test_deepcopy(self):
     friction.set_bullet_friction(bullet)
     friction.set_torsional(torsional)
     contact.set_collide_bitmask(0x12)
+    contact.set_category_bitmask(0x22)
     surface1.set_contact(contact)
     surface1.set_friction(friction)
 
     surface2 = copy.deepcopy(surface1)
     self.assertEqual(surface2.contact().collide_bitmask(), 0x12)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x22)
     self.assertEqual(surface2.friction().ode().mu(), 0.1)
     self.assertEqual(surface2.friction().ode().mu2(), 0.2)
     self.assertEqual(surface2.friction().ode().slip1(), 3)
@@ -300,9 +313,12 @@ def test_deepcopy(self):
     self.assertEqual(surface2.friction().torsional().ode_slip(), 0.01)
 
     contact.set_collide_bitmask(0x21)
+    contact.set_category_bitmask(0x33)
     surface1.set_contact(contact)
     self.assertEqual(surface1.contact().collide_bitmask(), 0x21)
     self.assertEqual(surface2.contact().collide_bitmask(), 0x12)
+    self.assertEqual(surface1.contact().category_bitmask(), 0x33)
+    self.assertEqual(surface2.contact().category_bitmask(), 0x22)
 
     ode.set_mu(1.1)
     ode.set_mu2(1.2)
@@ -363,14 +379,17 @@ def test_deepcopy(self):
   def test_default_contact_construction(self):
     contact = Contact()
     self.assertEqual(contact.collide_bitmask(), 0xFF)
+    self.assertFalse(contact.category_bitmask())
 
 
   def test_copy_contact_construction(self):
     contact1 = Contact()
     contact1.set_collide_bitmask(0x12)
+    contact1.set_category_bitmask(0x21)
 
     contact2 = Contact(contact1)
     self.assertEqual(contact2.collide_bitmask(), 0x12)
+    self.assertEqual(contact2.category_bitmask(), 0x21)
 
   def test_default_ode_construction(self):
     ode = ODE()
diff --git a/src/Surface.cc b/src/Surface.cc
index a0343ecf5..a13fa1823 100644
--- a/src/Surface.cc
+++ b/src/Surface.cc
@@ -30,9 +30,12 @@ using namespace sdf;
 
 class sdf::Contact::Implementation
 {
-  // \brief The bitmask used to filter collisions.
+  // \brief The collide bitmask used to filter collisions.
   public: uint16_t collideBitmask = 0xff;
 
+  // \brief The category bitmask used to filter collisions.
+  public: std::optional<uint16_t> categoryBitmask;
+
   /// \brief The SDF element pointer used during load.
   public: sdf::ElementPtr sdf{nullptr};
 };
@@ -605,6 +608,13 @@ Errors Contact::Load(ElementPtr _sdf)
         errors, "collide_bitmask"));
   }
 
+  if (_sdf->HasElement("category_bitmask"))
+  {
+    this->dataPtr->categoryBitmask =
+        static_cast<uint16_t>(_sdf->Get<unsigned int>(
+        errors, "category_bitmask"));
+  }
+
   // \todo(nkoenig) Parse the remaining collide properties.
   return errors;
 }
@@ -627,6 +637,18 @@ void Contact::SetCollideBitmask(const uint16_t _bitmask)
   this->dataPtr->collideBitmask = _bitmask;
 }
 
+/////////////////////////////////////////////////
+std::optional<uint16_t> Contact::CategoryBitmask() const
+{
+  return this->dataPtr->categoryBitmask;
+}
+
+/////////////////////////////////////////////////
+void Contact::SetCategoryBitmask(const uint16_t _bitmask)
+{
+  this->dataPtr->categoryBitmask = _bitmask;
+}
+
 /////////////////////////////////////////////////
 Surface::Surface()
   : dataPtr(gz::utils::MakeImpl<Implementation>())
@@ -724,6 +746,11 @@ sdf::ElementPtr Surface::ToElement(sdf::Errors &_errors) const
   sdf::ElementPtr contactElem = elem->GetElement("contact", _errors);
   contactElem->GetElement("collide_bitmask", _errors)->Set(
       _errors, this->dataPtr->contact.CollideBitmask());
+  if (this->dataPtr->contact.CategoryBitmask().has_value())
+  {
+    contactElem->GetElement("category_bitmask", _errors)->Set(
+        _errors, this->dataPtr->contact.CategoryBitmask().value());
+  }
 
   sdf::ElementPtr frictionElem = elem->GetElement("friction", _errors);
 
diff --git a/src/Surface_TEST.cc b/src/Surface_TEST.cc
index a7b2341d6..3a9e7ac5d 100644
--- a/src/Surface_TEST.cc
+++ b/src/Surface_TEST.cc
@@ -26,6 +26,7 @@ TEST(DOMsurface, DefaultConstruction)
   sdf::Surface surface;
   EXPECT_EQ(nullptr, surface.Element());
   EXPECT_EQ(surface.Contact()->CollideBitmask(), 0xFF);
+  EXPECT_FALSE(surface.Contact()->CategoryBitmask().has_value());
   EXPECT_EQ(surface.Contact()->Element(), nullptr);
   EXPECT_EQ(surface.Friction()->Element(), nullptr);
 }
@@ -44,11 +45,13 @@ TEST(DOMsurface, CopyOperator)
   sdf::Friction friction;
   friction.SetODE(ode);
   contact.SetCollideBitmask(0x12);
+  contact.SetCategoryBitmask(0x21);
   surface1.SetContact(contact);
   surface1.SetFriction(friction);
 
   sdf::Surface surface2(surface1);
   EXPECT_EQ(surface2.Contact()->CollideBitmask(), 0x12);
+  EXPECT_EQ(surface2.Contact()->CategoryBitmask(), 0x21);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu(), 0.1);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu2(), 0.2);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Slip1(), 3);
@@ -71,11 +74,13 @@ TEST(DOMsurface, CopyAssignmentOperator)
   sdf::Friction friction;
   friction.SetODE(ode);
   contact.SetCollideBitmask(0x12);
+  contact.SetCategoryBitmask(0x21);
   surface1.SetContact(contact);
   surface1.SetFriction(friction);
 
   sdf::Surface surface2 = surface1;
   EXPECT_EQ(surface2.Contact()->CollideBitmask(), 0x12);
+  EXPECT_EQ(surface2.Contact()->CategoryBitmask(), 0x21);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu(), 0.1);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu2(), 0.2);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Slip1(), 3);
@@ -92,9 +97,11 @@ TEST(DOMsurface, CopyAssignmentAfterMove)
 
   sdf::Contact contact1;
   contact1.SetCollideBitmask(0x12);
+  contact1.SetCategoryBitmask(0x21);
   surface1.SetContact(contact1);
   sdf::Contact contact2;
   contact2.SetCollideBitmask(0x34);
+  contact2.SetCategoryBitmask(0x43);
   surface2.SetContact(contact2);
 
   sdf::ODE ode1;
@@ -124,6 +131,8 @@ TEST(DOMsurface, CopyAssignmentAfterMove)
 
   EXPECT_EQ(surface2.Contact()->CollideBitmask(), 0x12);
   EXPECT_EQ(surface1.Contact()->CollideBitmask(), 0x34);
+  EXPECT_EQ(surface2.Contact()->CategoryBitmask(), 0x21);
+  EXPECT_EQ(surface1.Contact()->CategoryBitmask(), 0x43);
   EXPECT_DOUBLE_EQ(surface1.Friction()->ODE()->Mu(), 0.2);
   EXPECT_DOUBLE_EQ(surface1.Friction()->ODE()->Mu2(), 0.1);
   EXPECT_DOUBLE_EQ(surface1.Friction()->ODE()->Slip1(), 7);
@@ -165,6 +174,7 @@ TEST(DOMsurface, ToElement)
   torsional.SetODESlip(0.2);
   friction.SetTorsional(torsional);
   contact.SetCollideBitmask(0x12);
+  contact.SetCategoryBitmask(0x21);
   surface1.SetContact(contact);
   surface1.SetFriction(friction);
 
@@ -175,6 +185,7 @@ TEST(DOMsurface, ToElement)
   surface2.Load(elem);
 
   EXPECT_EQ(surface2.Contact()->CollideBitmask(), 0x12);
+  EXPECT_EQ(surface2.Contact()->CategoryBitmask(), 0x21);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu(), 0.1);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu2(), 0.2);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Slip1(), 3);
@@ -224,6 +235,7 @@ TEST(DOMsurface, ToElementErrorOutput)
   ode.SetFdir1(gz::math::Vector3d(1, 2, 3));
   friction.SetODE(ode);
   contact.SetCollideBitmask(0x12);
+  contact.SetCategoryBitmask(0x21);
   surface1.SetContact(contact);
   surface1.SetFriction(friction);
 
@@ -236,6 +248,7 @@ TEST(DOMsurface, ToElementErrorOutput)
   EXPECT_TRUE(errors.empty());
 
   EXPECT_EQ(surface2.Contact()->CollideBitmask(), 0x12);
+  EXPECT_EQ(surface2.Contact()->CategoryBitmask(), 0x21);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu(), 0.1);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Mu2(), 0.2);
   EXPECT_DOUBLE_EQ(surface2.Friction()->ODE()->Slip1(), 3);
@@ -254,6 +267,7 @@ TEST(DOMcontact, DefaultConstruction)
   sdf::Contact contact;
   EXPECT_EQ(nullptr, contact.Element());
   EXPECT_EQ(contact.CollideBitmask(), 0xFF);
+  EXPECT_FALSE(contact.CategoryBitmask().has_value());
   EXPECT_EQ(contact.Element(), nullptr);
 }
 
@@ -262,9 +276,11 @@ TEST(DOMcontact, CopyOperator)
 {
   sdf::Contact contact1;
   contact1.SetCollideBitmask(0x12);
+  contact1.SetCategoryBitmask(0x21);
 
   sdf::Contact contact2(contact1);
   EXPECT_EQ(contact2.CollideBitmask(), 0x12);
+  EXPECT_EQ(contact2.CategoryBitmask(), 0x21);
 }
 
 /////////////////////////////////////////////////
@@ -272,9 +288,11 @@ TEST(DOMcontact, CopyAssignmentOperator)
 {
   sdf::Contact contact1;
   contact1.SetCollideBitmask(0x12);
+  contact1.SetCategoryBitmask(0x21);
 
   sdf::Contact contact2 = contact1;
   EXPECT_EQ(contact2.CollideBitmask(), 0x12);
+  EXPECT_EQ(contact2.CategoryBitmask(), 0x21);
 }
 
 /////////////////////////////////////////////////
@@ -285,6 +303,8 @@ TEST(DOMcontact, CopyAssignmentAfterMove)
 
   contact1.SetCollideBitmask(0x12);
   contact2.SetCollideBitmask(0x34);
+  contact1.SetCategoryBitmask(0x21);
+  contact2.SetCategoryBitmask(0x43);
 
   sdf::Contact tmp = std::move(contact1);
   contact1 = contact2;
@@ -292,6 +312,8 @@ TEST(DOMcontact, CopyAssignmentAfterMove)
 
   EXPECT_EQ(contact2.CollideBitmask(), 0x12);
   EXPECT_EQ(contact1.CollideBitmask(), 0x34);
+  EXPECT_EQ(contact2.CategoryBitmask(), 0x21);
+  EXPECT_EQ(contact1.CategoryBitmask(), 0x43);
 }
 
 /////////////////////////////////////////////////
@@ -299,7 +321,9 @@ TEST(DOMcontact, CollideBitmask)
 {
   sdf::Contact contact;
   contact.SetCollideBitmask(0x67);
+  contact.SetCategoryBitmask(0x76);
   EXPECT_EQ(contact.CollideBitmask(), 0x67);
+  EXPECT_EQ(contact.CategoryBitmask(), 0x76);
 }
 
 /////////////////////////////////////////////////
diff --git a/test/integration/surface_dom.cc b/test/integration/surface_dom.cc
index f1f7faf94..d20425600 100644
--- a/test/integration/surface_dom.cc
+++ b/test/integration/surface_dom.cc
@@ -50,6 +50,7 @@ TEST(DOMSurface, Shapes)
   ASSERT_NE(nullptr, boxCol->Surface());
   ASSERT_NE(nullptr, boxCol->Surface()->Contact());
   EXPECT_EQ(boxCol->Surface()->Contact()->CollideBitmask(), 0xAB);
+  EXPECT_EQ(boxCol->Surface()->Contact()->CategoryBitmask(), 0xBA);
   EXPECT_DOUBLE_EQ(boxCol->Surface()->Friction()->ODE()->Mu(), 0.6);
   EXPECT_DOUBLE_EQ(boxCol->Surface()->Friction()->ODE()->Mu2(), 0.7);
   EXPECT_DOUBLE_EQ(boxCol->Surface()->Friction()->ODE()->Slip1(), 4);
diff --git a/test/sdf/shapes.sdf b/test/sdf/shapes.sdf
index 5a2e72d4f..e208e8a97 100644
--- a/test/sdf/shapes.sdf
+++ b/test/sdf/shapes.sdf
@@ -11,6 +11,7 @@
         <surface>
           <contact>
             <collide_bitmask>0xAB</collide_bitmask>
+            <category_bitmask>0xBA</category_bitmask>
           </contact>
           <friction>
               <ode>