Assessment is an important part of any psychologist’s role and the outcome can have consequences; positive and negative; for the person being assessed. The principles and practice of psychological assessment is a guide to drawing up; administering and interpreting assessment procedures; and judging whether the techniques used are theoretically and procedurally sound. It also takes a special look at assessment from an organisational perspective; because although many of the technical and scientific issues with respect to psychological assessment are common to all areas of applied psychology; there are numerous issues and applications that are unique to the organisational context. The principles and practice of psychological assessment is more of a “how to” than a critical text; but includes some background information and in-depth theorising for more problematic issues. A glossary of terms and a unique cognitive map of psychological tests are provided. Changes in this third edition include a new chapter on the history of assessment in South Africa; and the dominant narrative in some quarters that industrial psychologists set out deliberately to ensure the failure of some segments of the workforce. The principles and practice of psychological assessment is aimed at third year and honours students of psychology and industrial psychology as well as practitioners.