This review is prepared on the occasion of the 50th anniversary of the historic discovery of living anionic polymerization by Michael Szwarc. This process enabled preparation, with good control of polymer architecture, of well-defined polymers such as block and graft copolymers, star polymers, macrocycles, and functional polymers. Transformation reactions provide a facile route to synthesis of block copolymers that cannot be made by a single polymerization mode. A variety of transformation reactions involving step-growth, conventional and controlled free radical, cationic, anionic, group transfer, activated monomer Ziegler-Natta and metathesis reactions are known. In this article, transformation reactions involving living and controlled/living polymerization methods are reviewed. Other possibilities of combining different polymerization methods namely, macromonomer technique, coupling reactions, dual polymerizations and click chemistry are described. Preparation of star and miktoarm-star block copolymers by using mechanistic transformations is also presented. (c) 2006 Elsevier Ltd. All rights reserved.