This dissertation first confirms a hypothesis long held by financial economists. Working- and middle-class families earn substantially lower incomes than upper-class families for each dollar they invest in capital markets, because they invest mostly in real estate assets in contrast to upper-class families, who invest more in corporate securities. As a result, and as this dissertation illustrates, high levels of investment in real estate assets among working- and middle-class families is an important, but overlooked source of income inequality in America. As this dissertation also shows, however, working- and middle-class families have not always invested in real estate assets as much as they do today. These families began doing so in the late 1940s, though in the 1920s and 1930s, they had been steadily increasing their investments in corporate securities. This dissertation traces the cause of the 1940s shift in working- and middle-class investment practices to a change in the availability of installment credit options across asset classes that occurred between the mid-1930s and mid-1940s. During this period, installment credit options disappeared from securities markets, and soared in real estate markets. Working- and middle-class families responded to this change in credit opportunities by turning away from corporate securities as wealth-building vehicles, and by turning to real estate assets instead, because these families valued relying on installment plans to acquire assets, since such plans constituted ways of committing to the project of wealth-building. By identifying the role of disparities in credit access across asset classes as well as the importance of commitment in working- and middle-class saving strategies, this dissertation contributes both to the study of income inequality and to the sociology of asset choices.