Problems in validating ability tests for handicapped students and research approaches to predictive validity are discussed. Validity for handicapped persons tested under regular conditions; for applicants to special programs, and for tests taken under special administrative conditions are considered. Item analysis and the construction of new scales designed to improve validity are discussed. Construct validity studies to reveal the extent to which a test measures the same variables in handicapped and non-handicapped populations are suggested. Limitations in validation as a model for evaluating tests for the handicapped are discussed with various decision-making mechanisms and alternative perspectives of validation. (Author/CM)