Several social theorists describe a culture of self-entrepreneurialism: a subjectivity in which individuals see themselves as determining their objective economic outcomes or earnings. This culture, it is thought, is institutionalized in contemporary employment practices such that, as in human capital theory, self-entrepreneurialism is widespread among employees, and the more self-entrepreneurial earn more. I contribute a quantitative and comprehensive response to these largely untested claims using survey data from the mid-1990s through mid-2010s, representative of working-age Americans. I find individuals’ self-mastery, self-directedness, focus on self-growth and self-foresight of their future forms one general latent reflective self-concept. As a subjectivity, this self-entrepreneurialism is not associated with self-sufficiency or self-flexibility but is high among Americans regardless of social group. In terms of objective earnings, I find self-entrepreneurialism to be associated with an average earnings premium of up to ten percent of average earnings within occupations. However, self-entrepreneurialism does almost nothing to account for enduring earnings inequality between occupations. Further, over individuals’ working life, there is no association between increasing self-entrepreneurialism and increased earnings. Thus, in line with the theory of cultural capital, but not of human capital, self-entrepreneurialism works materially at work.