The synthesis of poly(styrene)-b-poly(butadiene)-b-poly(styrene) (SBS) and poly(methyl methacrylate)-b-poly(butadiene)-b-poly(methyl methacrylate) (MBM) triblock copolymers with poly(butadiene) (PBD) segments containing 100% 1,4-microstructure is described. Bis(allyl chloride) and bis(2-bromopropionate) terminated telechelic PBD＇s were synthesized by the ring-opening metathesis polymerization (ROMP) of 1,5-cyclooctadiene in the presence of the corresponding difunctional chain transfer agents. These telechelic PBDs were subsequently used as difunctional macroinitiators for the heterogeneous atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate to form SBS and MBM triblock copolymers. Triblock structure was confirmed by selective PBD degradation. In addition, the tandem ROMP-ATRP approach was successfully extended to a "one-pot" synthesis.