In this chapter, I outline the specialty of clinical geropsychology by first defining it and providing a brief history of the specialty. Then I summarize the knowledge base relevant to clinical geropsychology, including knowledge of the older population, adult development and aging, and clinical practice. The major activities of clinical geropsychologists-assessment, intervention, consultation, training, and research-are outlined, and the chapter concludes with a discussion of key achievements and future directions of clinical geropsychology.