This Handbook on Diversity and Inclusion Indices critically examines many of the popular and frequently cited indices related to diversity, equity and inclusion (DEI) benchmarking and progress tracking. The goal is to provide a better understanding of the indices' construction, strengths and weaknesses, intended applications, contribution to research and progress towards diversity and equity goals. The editors include detailed reviews of 23 DEI indices including broader, more general measures as well as those that focus on a particular aspect of diversity (e.g., gender, religion). Included are indices that measure diversity, equity, and/or inclusion at organizational, national, and regional levels. The Handbook unpacks this wide range of indices to meet the needs of researchers, public policy makers, and general consumers of information.