Book excerpt: Fully cross-referenced and source-referenced, this dictionary contains over 1200 entries consisting of terms concerning laws, theories, hypotheses, doctrines, principles, and effects in early and contemporary psychological literature. Each entry consists of the definition/description of the term with commentary, followed by a number of cross-referenced, related terms, and by chronologically-ordered source references to indicate the evolution of the term. An appendix provides supplementary material on many laws and theories not included in the dictionary itself and will be helpful to students and scholars concerned with specialty areas in psychology.