The mentally retarded, influenced by the same set of learning variables that influence and control much of the behavior of all humans, can experience a wide range of learning difficulties and deficits. He may experience—just as every other human may—a wide range of adaptive behavior problems in a wide range of settings. Prior to a discussion of the types of learning and behavior problems which confront the mentally retarded, it should prove helpful to comment on a few general characteristics of the retarded.