The issue of residential segregation has had a long history in the development of school desegregation laws and policies. Most social scientists and jurists would agree that school segregation is closely associated with racial segregation in housing, particularly in larger school systems. Residential segregation can give rise to school segregation between school systems, such as that existing between a predominantly minority city school system and its predominantly white suburban systems, and within a single school system when a neighborhood school policy reflects segregated residential patterns. The debate over the relationship between housing and school segregation arises, however, not from the mere fact of association, but from the causal interpretations applied to this association. Two major issues have framed the debates over this relationship. One issue concerns the causes of housing segregation itself, whether it arises primarily from discriminatory actions, either public or private, or from a complex set of social, economic, and demographic forces in which discrimination plays only a secondary role. The second issue focuses on the causal connections between school segregation and housing segregation and the direction of the causal relationship: the extent to which a neighborhood school policy actually contributes to housing segregation (rather than simply reflecting it) and the extent to which school desegregation contributes to integrated housing choices. On these points there is sharp disagreement between and within the social science and legal communities. The debates within the social science and legal communities have had reciprocating influences. On the one hand, a considerable amount of research on housing segregation has been generated by school desegregation litigation. On the other, a number of court decisions about the role of housing in school desegregation cases have been influenced by social science research and expert testimony. Thus the relationship between judicial policy and social science research is well illustrated by the housing segregation issue. The role of residential segregation in school desegregation law has itself passed through several stages during the past thirty years of school desegregation litigation.