Perfectly alternating unsaturated copolymers can be synthesized from a single monomer by being cognizant of the ADMET structure/reactivity relationships for substituted trienes. The Lewis acid free Schrock catalyst W(CHR’)(NAr)(OR)(2) in which Ar = 2,6-C6H3-i-Pr-2, R’ = CMe(2)Ph, and R = CMe(CF3)(2) is employed in this research where the tungsten catalyst’s inability to metathesize a trisubstituted olefin is exploited. The perfectly alternating nature of these polymers is clearly supported by H-1 and C-13 NMR spectroscopy as well as by W spectroscopy for the polymer obtained from 5,6-diphenyl-1,5,9-decatriene.