This document is part of a Bridgespan Group research project that focused on the question: "How could a philanthropist make the biggest improvement on social mobility with an investment of $1 billion?" In answering this question, the authors have sought to understand "what matters most" for improving social mobility outcomes. To do this, they have drawn from extensive research conducted by leading scholars in the field. They have also outlined a range of tools to assist philanthropists seeking systemic and field-level changes that go well beyond scaling direct service interventions. Using the research and identified tools, the authors have created an illustrative set of "bets" that provide concrete roadmaps for high-leverage investments of $1 billion with the potential for sustainable change at scale. The authors identified a list of 15 high-potential bets through which philanthropists could have a significant impact on increasing upward mobility. In identifying these bets, they sought to elevate investments that are particularly timely, suited to the unique role of philanthropy, have the potential to create significantly outsized impact, and, as a package, could truly sum to $1 billion. From this list, the authors have chosen to illustrate the following six investments: (1) Support holistic child development from birth through kindergarten; (2) Establish clear and viable pathways to careers; (3) Decrease rates of over-criminalization and over-incarceration; (4) Reduce unintended pregnancies; (5) Create place-based strategies to ensure access to opportunity across regions; and (6) Build the capacity of social-service delivery agencies to continuously learn and improve. This concept paper illustrates one of the six bets the authors have chosen to highlight. [For the main report, "'Billion Dollar Bets' to Create Economic Opportunity for Every American," see ED606509.]