By using the polymerization of acrylamide as an example, it is shown that solid state polymerization is in general just a special case of organic solid state reactions. Insofar aa the solid state aspects of the reaction are concerned, the reaction shows the expected behavior of an ordinary solid state reaction except that certain problems are exaggerated because of the large size of the product molecules involved and the large number of possible configurations the molecule may have. The reaction goes by a two phase mechanism with the polymer in general nucleating at a defect site. The product is noncrystalline because of the mismatch in geometry between the product molecule and parent lattice. The fact that the reaction mostly occurs at the interface between monomer and polymer where the reacting molecule cannot easily flip over probably also contributes to the frequent atacticity of the product. Annealing and recrystallization are factors which probably influence the over-all rate of reaction. The large molecular size of tho product and the frequently disordered nature of the product phase in polymerizations allows the use of some rather simple techniques in the study of solid state polymerizations making these good model systems for the study of some solid state problems.