A vinyl polymerizable UV light stabilizer comprising a compound of the formula: ##STR4## in which R is H or CH3 ; R1 is H or CH3 ; R and R1, are all such that the C???C double bond is vinyl polymerizable, R3 is a C1 -C5 alkyl radical, X is a linkage derived from the active isocyanate group reacted with an organic hydroxyl group or other active hydrogen moiety pendent from a UV light stabilizer; an