Linear very high molecular weight polyamides, such as nylons 6, 7 and 66, have been prepared via the rapid ring-opening polymerization (ROP) of their respective lactams catalyzed by super nonionic poly(aminophosphazene) and protophosphatrane bases. The super nonionic poly(aminophosphazene) bases appear to mimic catalysis by conventional anionic catalysts, but with the added advantage of the toleration of some degree of moisture. Multinuclear liquid and solid-state NMR experiments were used to probe the structure and proton transfer chemistry of P-4-t-Bu, one of the most effective lactam ROP poly(aminophosphazene) bases. P-31 magic-angle spinning (MAS) results showed the room-temperature structure of P-4-t-Bu to be-asymmetric and nonprotonated. Variable-temperature P-31 MAS NMR experiments on mixtures of P-4-t-Bu and epsilon-caprolactam demonstrated the proton transfer chemistry relevant for ROP at elevated temperature. This was confirmed by C-13 MAS NMR-observation of the epsilon-caprolactam anion in a cross-polarization experiment.