Inequality in education and other domains of life stands in the way of economic and civic progress in the United States. It forestalls social mobility and economic productivity and impairs social cohesion. As a result, national and international leaders--from big-city mayors to Pope Francis--recognize that, as President Obama (2013) put it, inequality is "the defining challenge of our time." Although inequality is pervasive, it can be addressed. One way to reduce inequality over time is to lessen the effects of inequality in one generation on the outcomes of the next. To address this challenge, the William T. Grant Foundation announced a new initiative to support research on programs, policies, and practices that reduce inequality in youth outcomes in the academic, social, behavioral, and economic realms. The Foundation's interest in inequality extends to many areas of youth development, reflecting disparities in arenas beyond education such as mental health, criminal justice, and workforce development (Alegria, Vallas, and Pumariega 2010; Fader, Kurlychek, and Morgan 2014; Schwartz, Ferguson, and Symonds 2010). This essay uses educational inequality to highlight new ways of thinking about inequality, key leverage points for reducing inequality, and the potential for research to develop more effective responses to inequality.