Radical initiation of methyl methacrylate polymerizations mediated by titanium amino-phenolate complexes gave exceptional control without the need for any cocatalyst or activator. The polymerization proceeds not by a classical controlled radical or coordination insertion mechanism but via a unique bimetallic group transfer process. Detailed experimental and computational studies support a polymerization mechanism with a titanium(IV)-enolate complex and a second titanium(III) complex that delivers an activated monomer and provides new insight into both titanium-mediated radical reactions and polymerizations.