Synthesis and living anionic ring-opening polymerization of 1,1-dipropylsilacyclobutane are reported. High molecular weight poly(dipropylsilylenepropylene) up to (M) over bar(n) = 83 900 g/mol (SEC/PS standards) with low polydispersity ((M) over bar(w)/(M) over bar(n) = 1.11 to 1.22) was obtained at -20 degrees C. End functionalization of poly(dipropylsilylenepropylene) with chlorodimethylvinylsilane and synthesis of block copolymers with styrene was achieved. The polymers were characterized with NMR, SEC, MALDI-TOF and DSC.