The American Bar Association-American Psychological Association (ABA-APA) Working Group on the Assessment of Capacity in Older Adults was established in 2003 under the auspices of the Task Force on Facilitating ABA-APA Relations. This handbook is designed for psychologists evaluating civil capacities of older adults. Contemporary probate law encourages functional assessments that describe task-specific deficits rather than global findings. With training in standardized cognitive and functional assessment, psychologists are in an ideal position to provide such evaluations. The specific goal of this handbook is to review psychological assessment of six civil capacities of particular importance to older adults, namely, medical consent capacity, sexual consent capacity, financial capacity, testamentary capacity, capacity to drive, and capacity to live independently. It also addresses the important topic of undue influence and introduces emerging areas of interest, such as the capacity to mediate, the capacity to participate in research, and the capacity to vote. [This work was funded by the Borchard Foundation Center on Law and Aging.]