The papers included in this volume were originally prepared for the Social Science Panel brought together by the Division of Behavioral Sciences of the National Research Council at the request of the National Academy of Sciences--National Academy of Engineering's Advisory Committee to the Department of Housing and Urban Development. The task of the Panel was to bring the existing behavioral and social science knowledge to bear on the question of the feasibility and desirability of "social mixing" in residential areas and, more particularly, in the Operation Breakthrough sites. Operation Breakthrough, a program of the Department of Housing and Urban Development, was conceived as a large-scale, experimental effort to overcome some of the existing technical barriers to creating an expanded supply of mass-produced housing of good quality. The following papers are included: "Attitudes on Race and Housing: a social-psychological view," Thomas F. Pettigrew; -Institutional and Contextual Factors Affecting the Housing Choices of Minority Residents," Donald L. Foley; "Factors Affecting Racial Mixing in Residential Areas," James S. Millen; "Social Stratification in Urban Areas," Cora B. Marrett; and, "Social Classes in Cities and Suburbs," Leo F. Schnore. (Author/JM)