The nucleation and growth of molecular crystals at interfaces has been investigated in the context of nucleation rates, growth orientation, nanoscale growth modes, and the influence of topographic features on growth characteristics. For instance, real time imaging of crystal growth in solution using the atomic force microscope (AFM) reveals that the nanoscopic surface topography and molecular structure of the crystal-solution interface play an important role in the growth and dissolution characteristics of molecular crystals. This influence can be understood in terms of the strength and orientation of intermolecular bonding at the crystal-solution interfaces. Additionally, the well- defined structure exposed on the surface of molecular single crystals can provide a unique substrate for heterogeneous crystal growth. Nucleation and growth of secondary crystalline phases on molecular crystals is both oriented and facile at certain substrate ledge sites, behavior which is attributed to lowering of the prenucleation aggregate free energy via "ledge directed epitaxy." The nucleation and growth of molecular crystals has also been studied on chemically modified surfaces. For instance, nucleation of malonic acid (HOOC-CH2- COOH) is significantly more rapid on organosulfur monolayers terminated with carboxylic acid groups than on corresponding monolayers terminated with methyl, methyl ester, or ethyl ester functionalities. In addition, the malonic acid crystals are oriented on these monolayers in a manner which is consistent with interfacial stabilization of malonic acid prenucleation aggregates by interfacial hydrogen bonding and surface polar forces, in contrast to monolayers in which hydrogen bonding functionality is absent. When taken together, these three complementary systems provide much insight into the interfacial forces controlling crystal growth.