Clinical neuropsychologists have few guidelines to assist them in determining if a change in a patient's performance across assessments was due to an intervention, maturation, practice effects or a combination of factors. This guide reviews the literature from 1970-1998 and has extracted and compiled all reported information on practice effects. Each table in this volume includes information on the subject/patient groups, then, gender, age, intervention, interval between assessments, scores at both assessment points, and the original reference citation. The tables are listed alphabetically for the 75 most widely used assessment instruments.