The investigation is part of continuing Navy research on the Trainability of Group IV (low ability) personnel intended to maximize the utilization and integration of marginal personnel in the fleet. An experimental Training Methods Development School (TMDS) was initiated to provide an experimental training program, with research controls, for evaluating the relative effectiveness of alternative training content and methods for such personnel. The TMDS curriculum is composed of courses in skill and knowledge areas which have been identified as most suitable and usable for newly assigned unrated personnel aboard ship. Trainees of the first three classes, representing the complete range of Group IV scores, were taught a variety of skills and knowledge (basic orientation, soldering, gauge and dial reading, basic hand tools, electronic equipment, practical mathematics) despite limitations in verbal and mathematical abilities. Successful training of marginal personnel appears to involve minimizing reliance on aptitudes which are known to be limited, and capitalizing on other important aptitudinal and experimental variables. (The document includes three references and seven figures and tables.) (author/ly)