This innovative and provocative volume focuses on the historical development of racial thinking and imagining in Mexico and the southwestern United States over a period of almost five centuries, from the earliest decades of Spanish colonial rule and the birth of a multiracial colonial population, to the present. The distinguished contributors to the volume bring into dialogue sophisticated new scholarship from an impressive range of disciplines, including social and cultural history, art history, legal studies, and performance art. The essays provide an engaging and original framework for understanding the development of racial thinking and classification in the region that was once New Spain and also shed new light on the history of the shifting ties between Mexico and the United States and the transnational condition of Latinos in the US today.