This three-volume handbook is a comprehensive presentation of the theory and application of tests in psychology and education. It begins with an in-depth portrayal of psychometrics: the quantitative underpinning of testing. It then provides thorough, up-to-date and informative chapters related to five general application areas of testing: (1) industrial/organizational psychology; (2) clinical psychology (including health psychology); (3) counseling psychology; (4) school psychology; and (5) educational testing. In each of these five areas, this handbook is probably the most comprehensive review of the use of testing and assessment in the subfield.