A SURVEY WAS PRESENTED OF SCIENTIFIC KNOWLEDGE ON AGE CHANGES IN HUMAN CAPACITIES, ESPECIALLY IN LEARNING ABILITY AND ADAPTABILITY, AND DESCRIBED VARIOUS METHODS USED TO TRAIN WORKERS OVER 40. THE ROLE OF MEMORY, MOTIVATION, RIGIDITY, AND INTELLIGENCE IN DETERMINING THE LEARNING EFFICIENCY OF MATURE ADULTS WAS ASSESSED, ALSO DIFFICULTIES CAUSED BY PACING, DIFFERENCES IN SKILL AND APTITUDE, AND INDIRECT RELATIONSHIP OF INFORMATION TO DESIRED ACTION. CASE HISTORIES OF SPECIAL TRAINING AND PLACEMENT SERVICES FOR OLDER WORKERS AND FOR THE LONG TERM UNEMPLOYED SUGGESTED THAT EFFECTIVE LEARNING DEPENDED HEAVILY ON SUITABLE CONDITIONS. OTHER EXPERIMENTS COMPARED INSTRUCTION VERSUS DEMONSTRATION, LEARNING FOR USE VERSUS RECAPITULATION, AND ACTIVITY LEARNING VERSUS MEMORIZING. FINDINGS SHOWED THAT, IF THE SETTING AND METHODS USED WERE ADAPTED TO CHANGING CAPACITIES AND NEEDS, LEARNING AND TRAINING WERE POSSIBLE EVEN IN LATE MATURITY. (INCLUDED ARE CHARTS AND PHOTOS, PROCEDURES FOR OVERCOMING SPECIFIC LEARNING DIFFICULTIES, SUGGESTIONS ON INTERPRETING EXPERIMENTAL DATA, AND 83 REFERENCES.) THIS DOCUMENT, NO. 18,251, IS AVAILABLE, FOR $2.00, FROM THE ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT, 2, RUE ANDRE-PASCAL, PARIS (16E), FRANCE. (LY)