Gene expression studies in psychiatric disorders have proven to be a useful partner to classic genetics approaches, and combined approaches such as convergent functional genomics (CFG) may provide shortcuts to the discovery of genes and overall understanding of the neurobiology involved. The combined approach has been applied with some success to bipolar disorder, alcoholism, and schizophrenia. For complete understanding of the illness, the analyses then need to be pursued at a biological pathway and mechanistic level, integrating environmental effects as key modulators of gene expression and phenotype manifestation. Progress in quantitative profiling of psychiatric phenotypes, and borrowing of concepts and paradigms from other medical fields that are farther along, such as cancer genetics and genomics, are exciting areas of advance for the near future. A (r)evolution in medical nosology in general, and psychiatric nosology in particular, will occur as a result of such studies.