This chapter includes a description of a number of possible environmental deficits which contribute to poor behavior development. The percentage of such persons in any given community is more dependent upon social and economic conditions of the community than upon any pronounced personal deficiencies of the retarded. The factors identified as underlying the educational and rehabilitation failures of these retardates are viewed basically as personal in nature rather than being related primarily to negative social or economic conditions in the environment. Educational and rehabilitation personnel are confronted with numerous behavioral deficits in clients who respond only minimally to the typical treatment services provided. A frequent consequence of the assumption that the major causes of behavioral inadequacies reside within some internal pathology or deviation is the position that treatment should be undertaken only by highly trained mental health specialists. The chapter also presents an overview of the key concepts discussed in this book.