In November of 1996, California voted and approved Proposition 209 (also known as the California Civil Rights Initiative) by a tally of 54.55% to 45.45%. It is unknown how many of those voters voted for the initiative because the name implied that it was pro-civil rights. Nonetheless, California became the first state to ban the practice of affirmative action through a ballot initiative. Several other states followed California's lead. This policy brief provides an overview of what is known about the impact of affirmative action bans nationally and complements research specific to California. It summarizes the impacts of affirmative action bans on admission of highly qualified applicants, diversity in higher education at highly selective and less selective institutions, in graduate and professional fields including science, technology, engineering, and mathematics (STEM) degrees, and in the pool of faculty. It also synthesizes research findings that document how alternate paths to diversity do not compensate for the absence of affirmative action.