Meta-block copolymers and a process for preparing a product mixture comprising meta-block copolymers by contacting a metathesis catalyst under metathesis conditions with a composition comprising two or more ethylenically unsaturated polymers, said unsaturation defining one or more polymer segments in each ethylenically unsaturated polymer, at least one polymer segment in at least one ethylenically unsaturated polymer being chemically distinguishable from at least one polymer segment in at least one other ethylenically unsaturated polymer, characterized in that each meta-block copolymer in the product mixture comprises a random distribution of said chemically distinguishable polymer blocks.