This second edition of a landmark reference resource - created not only for psychologists, clinicians, students, and professionals from allied mental health professions, but for all interested readers - offers definitive information on the lexicon of the field, including Almost 26,000 entries offering clear and authoritative definitions - approximately 1,000 more than the first edition Balanced coverage of 90 subareas, with significantly revised and expanded content especially in the areas of neuroscience, psychopharmacology, lifespan developmental psychology, statistics, experimental design, and many others Thousands of incisive cross-references that deepen the user's comprehension of related topics More than 400 brief biographical entries on historical figures in psychology and other related areas - four times more than the first edition A Guide to the Dictionary and a Quick Guide to Format that explain stylistic and format features Three appendixes: Institutional and Organizational Entries; Psychological Test and Assessment Instrument Entries; Psychotherapeutic Techniques, Biological Treatments, and Related Entries