We report the synthesis of >98% cis,isotactic and cis,syndiotactic polynorbornene (poly(NBE)) and poly(endo,anti-tetracyclododecene) (poly(TCD)). Cis,isotactic poly(NBE) and poly(TCD) were prepared employing Mo-based biphenolate imido alkylidene initiators, Mo(NR)(CHCMe2Ph)(Biphen) (Biphen = e.g., 3,3'-(t-Bu)2-5,5'-6,6'-(CH3)(4)-1,1'-biphenyl-2,2'-diolate), while cis,syndiotactic poly(NBE) and poly(TCD) were prepared employing W-based imido or oxo monoaryloxide pyrrolide (MAP) initiators, W(X)(CHR')(Pyrrolide)(OTer) (X = NR or O; OTer = a 2,6-terphenoxide). Addition of 1-hexene or coordinating solvents such as THF do not decrease the stereospecificity of the polymerization. Cis,iso and cis,syndio dyads can be distinguished through examination of H-1 and C-13 NMR spectra of the two polymers in a mixture. The polymers were hydrogenated to give isotactic and syndiotactic H-poly(NBE) and H-poly(TCD).