A series of cyclopentadiene (CPD)-based polymers and copolymers were synthesized by a controlled cationic polymerization of CPD. End-functionalized poly-(CPD) was synthesized with the HCl adducts [initiator = CH 3 CH(OCH 2 CH 2 X)Cl; X = Cl (2a), acetate (2b), or methacrylate] of vinyl ethers carrying pendant functional substituents X in conjunction with SnCl 4 (Lewis acid as a catalyst) and n-Bu 4 NCl (as an additive) in dichloromethane at -78 °C. The system led to the controlled cationic polymerizations of CPD to give controlled α-end-functionalized poly(CPD)s with almost quantitative attachment of the functional groups (F n ∼ 1). With the 2a or 2b/SnCl 4 /n-Bu 4 NCl initiating systems, diblock copolymers of 2-chloroethyl vinyl ether (CEVE) and 2-acetoxyethyl vinyl ether with CPD were also synthesized by the sequential polymerization of CPD and these vinyl ethers. An ABA-type triblock copolymer of CPD (A) and CEVE (B) was also prepared with a bifunctional initiator. The copolymerization of CPD and CEVE with 2a/SnCl 4 /n-Bu 4 NCl afforded random copolymers with controlled molecular weights and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.3-1.4).