Cities Lab is a collaborative research initiative to facilitate comparative social science research on metropolitan growth, sprawl, and spatial structure. Cities Lab makes it possible for scholars interested in urban geography, economics, sociology, and related disciplines to share and use comparable data on cities around the globe. The Cities Lab server hosts over 90 gigabytes of Census, raster image, and other data at the small-area level for metropolitan areas across Canada, America, Mexico, and other nations. Cities Lab is directed by John R. Miron, Professor of Geography and City Studies, Department of Social Sciences, University of Toronto at Scarborough. Funding for Cities Lab has come from grants from the Social Sciences and Humanities Research Council of Canada. The ongoing support of the Department of Social Sciences is also gratefully acknowledged.