Social class and ethnic-group membership have been found to be associated with a wide variety of personality, motivational, cognitive, and achievement behaviors in children in our society. The most consistent and frequently noted finding is that lower-class and minority group children generaIly perform less weIl than white middle-class children on standardized measures of intelligence and achievement. In this volume the authors believe that it is time for behavioral scientists to reject the deficit model and to adopt in its place a difference approach in which no group is considered to be inferior or superior to any other and in which differences among groups are viewed instead as important empirical phenomena to be investigated.