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, the authors 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. From a list of 15 high-potential bets through which philanthropists could have a significant impact on increasing upward mobility, six bets were selected 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. This concept paper illustrates one of the six bets. The paper discusses potential solutions to reducing unintended pregnancies in the United States. It focuses on building a national initiative that encourages and supports young women and their partners to make informed decisions about when to have a child and improving access to the most effective contraceptive methods. It also outlines the potential of seven investments philanthropists could make to improve and grow promising programs and to shift incentives and behaviors in an effort to reduce unintended pregnancies. Lastly, it puts the investments into economic perspective, quantifying their projected impact on the lifetime earnings of individuals and their families and highlighting for philanthropists the return on investment of such commitments. [For the main report, "'Billion Dollar Bets' to Create Economic Opportunity for Every American," see ED606509.]