Residential and school segregation are key barriers to social mobility and equal opportunity. A first step in tackling segregation is an accurate accounting of its trends and patterns, but we currently lack a centralized segregation data resource. The principal investigors will create the Segregation Lab, a publicly-available, comprehensive, longitudinal database of estimates of residential and school segregation by race/ethnicity and economic status. The segregation database and associated suite of data products will provide improved source data, tools for addressing boundary issues, and protocols for reducing estimation bias. The Segregation Lab will build capacity for research on the role of segregation in producing and exacerbating social inequality in the lives of children and families.