Although molecular imprinting in organic polymers was introduced by Wulff more than 30 years ago,(1) this promising technology has yet to realize its full commercial potential, partially due to the lack of a clear understanding of how physical factors affect the polymerization process and what basic rules should be applied in order to produce synthetic receptors with the required characteristics. This arises mainly from the complex nature of the polymerization reaction in cross-linked systems which depends on many interrelated factors. Among the most important physical factors affecting the polymerization process, as well as the recognition properties of the materials produced, are temperature, type of initiation, pressure, magnetic field, volume of the polymerization mixture, dielectric constants of monomers and solvent, and polymerization time. This paper was inspired by the urgent need to summarize the knowledge generated concerning how polymerization conditions affect the quality of molecularly imprinted polymers (MIPs) in order to help the imprinting community make rational and effective choices and maximize their chances for success.