Part 2 of a 4 part series. In the second part of this series, Joseph Vander Veer traces the historical evolution of behavioral disorders and psychopharmacology; patterns of behavior in affective disorders; lithium therapy for manic-depressive problems; and drug therapy for depression. Vander Veer concludes the article with a glossary of terms related to psychopharmacology. Part 1 is in JPP 3:2, Part 2 is in JPP 3:3, Part 3 is in JPP 3:4, Part 4 is in JPP 4:1.