This monograph is an account of two related investigations of the motor domain and its correlates in educationally handicapped children. Part I describes an investigation primarily concerned with the identification of the basic components of the motor behavior of educable mentally retarded children through the use of factor analysis techniques. The hypothesized factor structure included: static muscular strength; explosive muscular strength; muscular strength-endurance; gross body coordination; cardio-respiratory endurance; limb-eye coordination; manual dexterity; static balance; kinesthesis; flexibility; speed and coordination of gross limb movements; body fat; and body size. The basic premise underlying this investigation is that man's motor capabilities are in part made up of a number of general abilities, many of which provide the foundation upon which specific motor traits are built. Part II is a report of an experiment designed to determine the effects of individualized versus group-oriented physical education programs upon selected parameters of the development of educable mentally retarded and minimally brain injured children. Assessments were made of changes in measures of motor, intellectual, social, and emotional development of educable mentally retarded and minimally brain injured children exposed to 20 weeks of daily instruction in physical education in contrast to control groups. Each of the studies is followed by a bibliography. The appendixes contain: a table of reliabilities of motor performance measures; table of intercorrelations upon which the factor analyses are based; the individualized education program; and the art program. (MM)