With the goal of motivating a broader swath of philanthropists to make well-informed, actionable "big bets" to catalyze dramatic improvements in social mobility in the United States, a Bridgespan Group team spent a year researching and developing prototypes of potential large-scale investments that aim to build pathways to the middle class for millions of Americans. This overview of research: (1) discusses the three main goals of the project; (2) describes the research process; and (3) provides a list of interviewees. [For the main report, see ED606509.]