Molecular self-assembly of supported monolayers can produce a variety of structures with different types of surface functional groups and with varied topography. Such structural flexibility promises many applications. In addition, strategies for precision chemical patterning have evolved which expand the possibilities. Real applications of these monolayers will require precise control of structural features which in turn depends critically upon improved understanding of such factors as formation mechanisms and mixed composition phase stability. Recent advances show that such an understanding should evolve in the future.