diff --git a/develop/untests/registry_untests.lua b/develop/untests/registry_untests.lua
index f103e07..efc73cd 100644
--- a/develop/untests/registry_untests.lua
+++ b/develop/untests/registry_untests.lua
@@ -415,6 +415,50 @@ do
     end
 end
 
+do
+    local f1, f2 = evo.registry.entity(), evo.registry.entity()
+
+    local e1 = evo.registry.entity():set(f1, 10)
+    local e2 = evo.registry.entity():set(f1, 15)
+    local e3 = evo.registry.entity():set(f1, 20):set(f2, 40)
+    local e4 = evo.registry.entity():set(f1, 25):set(f2, 45)
+
+    do
+        local q = evo.registry.query(f2)
+        assert(2 == evo.registry.batch_assign(q, f1, 42))
+        assert(e1:get(f1) == 10 and e2:get(f1) == 15 and e3:get(f1) == 42 and e4:get(f1) == 42)
+        assert(e3:get(f2) == 40 and e4:get(f2) == 45)
+    end
+
+    do
+        local q = evo.registry.query(f1)
+        assert(4 == evo.registry.batch_assign(q, f1, 21))
+        assert(e1:get(f1) == 21 and e2:get(f1) == 21 and e3:get(f1) == 21 and e4:get(f1) == 21)
+        assert(e3:get(f2) == 40 and e4:get(f2) == 45)
+    end
+
+    do
+        local q = evo.registry.query(f1, f2)
+        assert(2 == evo.registry.batch_assign(q, f1, nil))
+        assert(e1:get(f1) == 21 and e2:get(f1) == 21 and e3:get(f1) == true and e4:get(f1) == true)
+        assert(e3:get(f2) == 40 and e4:get(f2) == 45)
+    end
+
+    do
+        local q = evo.registry.query(f1)
+        assert(2 == evo.registry.batch_assign(q, f2, 42))
+        assert(e1:get(f1) == 21 and e2:get(f1) == 21 and e3:get(f1) == true and e4:get(f1) == true)
+        assert(e3:get(f2) == 42 and e4:get(f2) == 42)
+    end
+
+    do
+        local q = evo.registry.query(f1):exclude(f2)
+        assert(2 == evo.registry.batch_assign(q, f1, 84))
+        assert(e1:get(f1) == 84 and e2:get(f1) == 84 and e3:get(f1) == true and e4:get(f1) == true)
+        assert(e3:get(f2) == 42 and e4:get(f2) == 42)
+    end
+end
+
 do
     local f1, f2 = evo.registry.entity(), evo.registry.entity()
 
diff --git a/evolved/registry.lua b/evolved/registry.lua
index e3afa16..9912b3b 100644
--- a/evolved/registry.lua
+++ b/evolved/registry.lua
@@ -575,7 +575,31 @@ end
 ---@param component any
 ---@return integer assigned_count
 function registry.batch_assign(query, fragment, component)
-    error('not impl yet', 2)
+    component = component == nil and true or component
+
+    ---@type evolved.chunk[]
+    local chunks = {}
+
+    for chunk in registry.execute(query) do
+        if chunk.__components[fragment] ~= nil then
+            chunks[#chunks + 1] = chunk
+        end
+    end
+
+    local assigned_count = 0
+
+    for _, chunk in ipairs(chunks) do
+        local components = chunk.__components[fragment]
+        local component_count = #components
+
+        assigned_count = assigned_count + component_count
+
+        for i = 1, component_count do
+            components[i] = component
+        end
+    end
+
+    return assigned_count
 end
 
 ---@param entity evolved.entity