Opportunity has long been the bedrock of American society. Today, however, the solid foundation that once grounded the lives of millions is fracturing along economic and social lines. Human capital, encompassing a broad set of cognitive and interpersonal skills, has become increasingly important in determining labor market outcomes as the evolving economic landscape, shaped by the interplay of globalization and technology, as well as governmental and business policies, changes who is working and what they are paid. There is now also a tighter link between human and social capital, which is the set of networks, norms, and values that serve to foster development and success. The strengthening of this relationship has contributed to a polarization in the accumulation of human and social capital that translates into distinctly different life outcomes for individuals. This changing landscape also affects the intergenerational transmission of opportunity, with children's circumstances at birth becoming more determinative of their prospects as adults. This introduction sets the stage for the chapters that follow, which offer perspectives on opportunity from fi elds ranging from education and demography to economics and political science. The authors of these chapters, national leaders in their fi elds, offer their insights into policies and practices that could help us move forward to improve equality of opportunity and better realize America's values and ideals.