The anionic polymerization of caprolactam (with sodium hydride and acetyl caprolactam as catalysts) carried out in glass ampules is reported. The effect of the catalyst concentration, polymerization temperature, and other variables was studied. Polymerization of caprolactam at temperatures around 120°C. in a paraffin suspension, in which the paraffin was introduced into a syrupy prepolymer is also reported. The influence of a few variables on conversion, molecular weight, particle size distribution, is discussed. Both viscosity and conversion are always lower in suspension than in bulk polymerization. Polymer granules of a wide range of dimensions which generally contain some residual monomer (unlike the bulk polymerization) are obtained in suspension polymerization. The above results are discussed and some interpretations are suggested.