diff --git a/src/api/physics.c b/src/api/physics.c
index 6fb22dd5..416f7615 100644
--- a/src/api/physics.c
+++ b/src/api/physics.c
@@ -33,7 +33,27 @@ int l_lovrPhysicsInit(lua_State* L) {
 }
 
 int l_lovrPhysicsNewWorld(lua_State* L) {
-  World* world = lovrWorldCreate();
+  float xg = luaL_optnumber(L, 1, 0.f);
+  float yg = luaL_optnumber(L, 2, -9.81);
+  float zg = luaL_optnumber(L, 3, 0.f);
+  int allowSleep = lua_gettop(L) < 4 || lua_toboolean(L, 4);
+  const char* tags[16];
+  int tagCount;
+  if (lua_type(L, 5) == LUA_TTABLE) {
+    tagCount = lua_objlen(L, 5);
+    for (int i = 0; i < tagCount; i++) {
+      lua_rawgeti(L, -1, i + 1);
+      if (lua_isstring(L, -1)) {
+        tags[i] = lua_tostring(L, -1);
+      } else {
+        return luaL_error(L, "World tags must be a table of strings");
+      }
+      lua_pop(L, 1);
+    }
+  } else {
+    tagCount = 0;
+  }
+  World* world = lovrWorldCreate(xg, yg, zg, allowSleep, tags, tagCount);
   luax_pushtype(L, World, world);
   return 1;
 }
diff --git a/src/api/types/collider.c b/src/api/types/collider.c
index cda56831..10b302c3 100644
--- a/src/api/types/collider.c
+++ b/src/api/types/collider.c
@@ -449,6 +449,27 @@ int l_lovrColliderSetRestitution(lua_State* L) {
   return 0;
 }
 
+int l_lovrColliderGetTag(lua_State* L) {
+  Collider* collider = luax_checktype(L, 1, Collider);
+  lua_pushstring(L, lovrColliderGetTag(collider));
+  return 1;
+}
+
+int l_lovrColliderSetTag(lua_State* L) {
+  Collider* collider = luax_checktype(L, 1, Collider);
+  if (lua_isnoneornil(L, 2)) {
+    lovrColliderSetTag(collider, NULL);
+    return 0;
+  }
+
+  const char* tag = luaL_checkstring(L, 2);
+  if (lovrColliderSetTag(collider, tag)) {
+    return luaL_error(L, "Invalid tag %s", tag);
+  }
+
+  return 0;
+}
+
 const luaL_Reg lovrCollider[] = {
   { "destroy", l_lovrColliderDestroy },
   { "getWorld", l_lovrColliderGetWorld },
@@ -495,5 +516,7 @@ const luaL_Reg lovrCollider[] = {
   { "setFriction", l_lovrColliderSetFriction },
   { "getRestitution", l_lovrColliderGetRestitution },
   { "setRestitution", l_lovrColliderSetRestitution },
+  { "getTag", l_lovrColliderGetTag },
+  { "setTag", l_lovrColliderSetTag },
   { NULL, NULL }
 };
diff --git a/src/api/types/world.c b/src/api/types/world.c
index af7f6ddf..86f4ad44 100644
--- a/src/api/types/world.c
+++ b/src/api/types/world.c
@@ -200,6 +200,30 @@ int l_lovrWorldRaycast(lua_State* L) {
   return 0;
 }
 
+int l_lovrWorldDisableCollisionBetween(lua_State* L) {
+  World* world = luax_checktype(L, 1, World);
+  const char* tag1 = luaL_checkstring(L, 2);
+  const char* tag2 = luaL_checkstring(L, 3);
+  lovrWorldDisableCollisionBetween(world, tag1, tag2);
+  return 0;
+}
+
+int l_lovrWorldEnableCollisionBetween(lua_State* L) {
+  World* world = luax_checktype(L, 1, World);
+  const char* tag1 = luaL_checkstring(L, 2);
+  const char* tag2 = luaL_checkstring(L, 3);
+  lovrWorldEnableCollisionBetween(world, tag1, tag2);
+  return 0;
+}
+
+int l_lovrWorldIsCollisionEnabledBetween(lua_State* L) {
+  World* world = luax_checktype(L, 1, World);
+  const char* tag1 = luaL_checkstring(L, 2);
+  const char* tag2 = luaL_checkstring(L, 3);
+  lua_pushboolean(L, lovrWorldIsCollisionEnabledBetween(world, tag1, tag2));
+  return 1;
+}
+
 const luaL_Reg lovrWorld[] = {
   { "newCollider", l_lovrWorldNewCollider },
   { "newBoxCollider", l_lovrWorldNewBoxCollider },
@@ -220,5 +244,8 @@ const luaL_Reg lovrWorld[] = {
   { "isSleepingAllowed", l_lovrWorldIsSleepingAllowed },
   { "setSleepingAllowed", l_lovrWorldSetSleepingAllowed },
   { "raycast", l_lovrWorldRaycast },
+  { "disableCollisionBetween", l_lovrWorldDisableCollisionBetween },
+  { "enableCollisionBetween", l_lovrWorldEnableCollisionBetween },
+  { "isCollisionEnabledBetween", l_lovrWorldIsCollisionEnabledBetween },
   { NULL, NULL }
 };
diff --git a/src/physics/physics.c b/src/physics/physics.c
index d701a793..8c1930e6 100644
--- a/src/physics/physics.c
+++ b/src/physics/physics.c
@@ -42,7 +42,7 @@ void lovrPhysicsDestroy() {
   dCloseODE();
 }
 
-World* lovrWorldCreate() {
+World* lovrWorldCreate(float xg, float yg, float zg, int allowSleep, const char** tags, int tagCount) {
   World* world = lovrAlloc(sizeof(World), lovrWorldDestroy);
   if (!world) return NULL;
 
@@ -51,6 +51,16 @@ World* lovrWorldCreate() {
   dHashSpaceSetLevels(world->space, -4, 8);
   world->contactGroup = dJointGroupCreate(0);
   vec_init(&world->overlaps);
+  lovrWorldSetGravity(world, xg, yg, zg);
+  lovrWorldSetSleepingAllowed(world, allowSleep);
+  map_init(&world->tags);
+  for (int i = 0; i < tagCount; i++) {
+    map_set(&world->tags, tags[i], i);
+  }
+
+  for (int i = 0; i < MAX_TAGS; i++) {
+    world->masks[i] = ~0;
+  }
 
   return world;
 }
@@ -111,10 +121,14 @@ int lovrWorldCollide(World* world, Shape* a, Shape* b, float friction, float res
     return 0;
   }
 
-  dContact contacts[MAX_CONTACTS];
-
   Collider* colliderA = a->collider;
   Collider* colliderB = b->collider;
+  int tag1 = colliderA->tag;
+  int tag2 = colliderB->tag;
+
+  if (tag1 != NO_TAG && tag2 != NO_TAG && !((world->masks[tag1] & (1 << tag2)) && (world->masks[tag2] & (1 << tag1)))) {
+    return 0;
+  }
 
   if (friction < 0) {
     friction = sqrt(colliderA->friction * colliderB->friction);
@@ -124,6 +138,7 @@ int lovrWorldCollide(World* world, Shape* a, Shape* b, float friction, float res
     restitution = MAX(colliderA->restitution, colliderB->restitution);
   }
 
+  dContact contacts[MAX_CONTACTS];
   for (int i = 0; i < MAX_CONTACTS; i++) {
     contacts[i].surface.mode = 0;
     contacts[i].surface.mu = friction;
@@ -197,6 +212,56 @@ void lovrWorldRaycast(World* world, float x1, float y1, float z1, float x2, floa
   dGeomDestroy(ray);
 }
 
+const char* lovrWorldGetTagName(World* world, int tag) {
+  if (tag == NO_TAG) {
+    return NULL;
+  }
+
+  const char* key;
+  map_iter_t iter = map_iter(&world->tags);
+  while ((key = map_next(&world->tags, &iter))) {
+    if (*map_get(&world->tags, key) == tag) {
+      return key;
+    }
+  }
+
+  return NULL;
+}
+
+int lovrWorldDisableCollisionBetween(World* world, const char* tag1, const char* tag2) {
+  int* index1 = map_get(&world->tags, tag1);
+  int* index2 = map_get(&world->tags, tag2);
+  if (!index1 || !index2) {
+    return NO_TAG;
+  }
+
+  world->masks[*index1] &= ~(1 << *index2);
+  world->masks[*index2] &= ~(1 << *index1);
+  return 0;
+}
+
+int lovrWorldEnableCollisionBetween(World* world, const char* tag1, const char* tag2) {
+  int* index1 = map_get(&world->tags, tag1);
+  int* index2 = map_get(&world->tags, tag2);
+  if (!index1 || !index2) {
+    return NO_TAG;
+  }
+
+  world->masks[*index1] |= (1 << *index2);
+  world->masks[*index2] |= (1 << *index1);
+  return 0;
+}
+
+int lovrWorldIsCollisionEnabledBetween(World* world, const char* tag1, const char* tag2) {
+  int* index1 = map_get(&world->tags, tag1);
+  int* index2 = map_get(&world->tags, tag2);
+  if (!index1 || !index2) {
+    return NO_TAG;
+  }
+
+  return (world->masks[*index1] & (1 << *index2)) && (world->masks[*index2] & (1 << *index1));
+}
+
 Collider* lovrColliderCreate(World* world) {
   if (!world) {
     error("No world specified");
@@ -209,6 +274,7 @@ Collider* lovrColliderCreate(World* world) {
   collider->world = world;
   collider->friction = 0;
   collider->restitution = 0;
+  collider->tag = NO_TAG;
   dBodySetData(collider->body, collider);
   vec_init(&collider->shapes);
   vec_init(&collider->joints);
@@ -539,6 +605,26 @@ void lovrColliderGetAABB(Collider* collider, float aabb[6]) {
   }
 }
 
+const char* lovrColliderGetTag(Collider* collider) {
+  return lovrWorldGetTagName(collider->world, collider->tag);
+}
+
+int lovrColliderSetTag(Collider* collider, const char* tag) {
+  if (tag == NULL) {
+    collider->tag = NO_TAG;
+    return 0;
+  }
+
+  int* index = map_get(&collider->world->tags, tag);
+
+  if (!index) {
+    return NO_TAG;
+  }
+
+  collider->tag = *index;
+  return 0;
+}
+
 void lovrShapeDestroy(const Ref* ref) {
   Shape* shape = containerof(ref, Shape);
   lovrShapeDestroyData(shape);
diff --git a/src/physics/physics.h b/src/physics/physics.h
index a76a59f1..ef929d26 100644
--- a/src/physics/physics.h
+++ b/src/physics/physics.h
@@ -1,11 +1,14 @@
 #include "util.h"
 #include "lib/vec/vec.h"
+#include "lib/map/map.h"
 #include <stdint.h>
 #include <ode/ode.h>
 
 #pragma once
 
 #define MAX_CONTACTS 4
+#define MAX_TAGS 16
+#define NO_TAG ~0
 
 typedef enum {
   SHAPE_SPHERE,
@@ -26,6 +29,8 @@ typedef struct {
   dSpaceID space;
   dJointGroupID contactGroup;
   vec_void_t overlaps;
+  map_int_t tags;
+  uint16_t masks[MAX_TAGS];
 } World;
 
 typedef struct {
@@ -33,6 +38,7 @@ typedef struct {
   dBodyID body;
   World* world;
   void* userdata;
+  int tag;
   vec_void_t shapes;
   vec_void_t joints;
   float friction;
@@ -74,7 +80,7 @@ typedef struct {
 void lovrPhysicsInit();
 void lovrPhysicsDestroy();
 
-World* lovrWorldCreate();
+World* lovrWorldCreate(float xg, float yg, float zg, int allowSleep, const char** tags, int tagCount);
 void lovrWorldDestroy(const Ref* ref);
 void lovrWorldDestroyData(World* world);
 void lovrWorldUpdate(World* world, float dt, CollisionResolver resolver, void* userdata);
@@ -90,6 +96,10 @@ void lovrWorldSetAngularDamping(World* world, float damping, float threshold);
 int lovrWorldIsSleepingAllowed(World* world);
 void lovrWorldSetSleepingAllowed(World* world, int allowed);
 void lovrWorldRaycast(World* world, float x1, float y1, float z1, float x2, float y2, float z2, RaycastCallback callback, void* userdata);
+const char* lovrWorldGetTagName(World* world, int tag);
+int lovrWorldDisableCollisionBetween(World* world, const char* tag1, const char* tag2);
+int lovrWorldEnableCollisionBetween(World* world, const char* tag1, const char* tag2);
+int lovrWorldIsCollisionEnabledBetween(World* world, const char* tag1, const char* tag);
 
 Collider* lovrColliderCreate();
 void lovrColliderDestroy(const Ref* ref);
@@ -140,6 +150,8 @@ float lovrColliderGetFriction(Collider* collider);
 void lovrColliderSetFriction(Collider* collider, float friction);
 float lovrColliderGetRestitution(Collider* collider);
 void lovrColliderSetRestitution(Collider* collider, float restitution);
+const char* lovrColliderGetTag(Collider* collider);
+int lovrColliderSetTag(Collider* collider, const char* tag);
 
 void lovrShapeDestroy(const Ref* ref);
 void lovrShapeDestroyData(Shape* shape);