AbstractThe anionic polymerization of 2‐pyrrolidone (PD) was initiated with the potassium salt of PD at 30–50°C and accelerated with the followingN‐iminolactams (NIL): 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone(1), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐2‐pyrrolidone(2), 1‐(1‐azacyclonon‐1‐en‐2‐yl)‐2‐pyrrolidone(4), 1‐(1‐azacyclohept‐1‐en‐2‐yl)‐1‐ azacycloheptan‐2‐one(3)and 1‐(phenyliminomethyl)‐2‐pyrrolidone(5). The polymerizations exhibit formal kinetics of zero order with respect to the monomer with substantially differing apparent rate constants depending on the type of NIL used. The same limit conversions are attained in a