This chapter introduces the basic principle and the synthetic aspects of molecular imprinting. First, the use of a molecular template to guide the location of functional groups inside molecularly imprinted cavities is explained. Three different mechanisms that ensure a molecular template associates with functional monomers or the imprinted polymers, that is, through reversible covalent, noncovalent, and sacrificial covalent bonds, are then described. The main focus is put on noncovalent molecular imprinting using free radical polymerization. The merits of using classical radical polymerization and more sophisticated, controlled radical polymerization are analyzed. After these synthetic chemistry aspects, the chapter continues to discuss the different polymerization processes that can be used to prepare well-defined polymer monoliths, microspheres, and nanoparticles. New top-down processing techniques that produce micro- and nanopatterns of imprinted polymers are also reviewed. The chapter finishes with a brief introduction to using imprinted polymers as building blocks to construct new functional materials and devices, which we consider as one important direction for further development.