The Black Lives Matter (BLM) movement arose to put a much-needed spotlight on police brutality and systemic racism. In two comprehensive studies, we sought to investigate the determinants of support for the BLM movement. First, in a systematic review 1,588 records were identified and findings from twenty-four studies (Npooled=27,691) were narratively synthesized along five categories relating to demographics, race, partisanship and ideology, discrimination and prejudice, and psychology. Second, we exhaustively examined the determinants of BLM support across thirteen probability-based nationally representative datasets (Npooled=31,779), finding thirty-seven common predictors for which individual meta-analyses were conducted to estimate the strength and robustness of their associations. Our results suggest a near perfect match between BLM opposition and positive attitudes towards political actors and institutions rooted in systemic racism in the United States. The present work contributes to a broad categorization of correlates of support for BLM across social, psychological, and political domains.