diff --git a/docs/src/types.md b/docs/src/types.md
index a8f40f4d..2acd2e9f 100644
--- a/docs/src/types.md
+++ b/docs/src/types.md
@@ -22,6 +22,7 @@ isrealpart
 isimagpart
 isconj
 ordinary_variable
+is_commutative
 ```
 
 ## Monomials
diff --git a/src/variable.jl b/src/variable.jl
index 709d6c86..87e64a03 100644
--- a/src/variable.jl
+++ b/src/variable.jl
@@ -40,6 +40,17 @@ This operation is not type stable for the TypedPolynomials implementation if `nv
 """
 variable(t::_APL) = convert(variable_union_type(t), t)
 
+"""
+    is_commutative(::Type{<:AbstractVariable})::Bool
+
+Returns whether variables of the given type are commutative, i.e., whether
+`x * y == y * x`.
+"""
+function is_commutative end
+is_commutative(p::_APL) = is_commutative(typeof(p))
+is_commutative(v::AbstractVector) = is_commutative(eltype(v))
+is_commutative(v::Tuple) = all(is_commutative, v)
+
 """
     name(v::AbstractVariable)::AbstractString