In-depth interviews with 62 people with working class ties (blue-collar workers and adult sons and daughters of blue-collar workers) reveal a social construction of working class that imbues it with four core, positively valenced values: strong work ethic, provider orientation, the dignity of all work and workers, and humility. This constellation of values is communicated through a ubiquitous macrolevel discourse—which I coin the Working Class Promise—that elevates working class to the highest position in the social class hierarchy and fosters a strong commitment to maintain a working class value system and identity. However, this social construction is only a partial social construction. That is, these individuals do not question material, socioeconomic-based delineations of class boundaries (e.g., income, education level, occupational prestige). Consequently, their acceptance of structural class boundaries, combined with their high regard of working class values, positions social classes in ways that make the goals of the American Dream (i.e., class mobility) and the Working Class Promise (i.e., class maintenance) paradoxical. I argue that the paradox of social mobility that results from this partial social construction is the root of mobility-based ambivalences.