Education is considered the main upward mobility pathway, but even with comparable education and level of competence, workers with lower socioeconomic status (SES) origins are disadvantaged in terms of earnings and occupational attainment. This problem has been labeled the “class ceiling,” highlighting the parallel with the “glass ceiling” faced by women. To shed light on the problem, in a series of projects forming part of my dissertation, I focused on where the problem starts, key career transition stages (i.e., first internship, first job), and sought to complement extant knowledge on class issues by taking a supply side (agentic) perspective. I first extend past work by proposing that underrepresentation in creative jobs acts as a mechanism that may explain the class achievement gap down the line, but provide a different, novel explanation for the problem. Across a series of studies and methodological approaches, I find evidence of self-selection that suggests the issue is more extensive and deeply rooted (arguably involving processes in education and early-life socialization) than simple labor market discrimination that has been the focus of past work. Second, I conduct an in-depth, year-long longitudinal investigation of causes of the class challenges beyond entry, comparing the relevance of demand-side and supply-side processes in challenges faced by workers with lower SES origins. I find that discrimination and other demand-side processes matter little, and that many challenges stem from workers’ own psychology. Finally, given these insights that early-stage sources of the class ceiling, are figuratively speaking, at least partly in the mind, I endeavored to improve adjustment and labor market outcomes of workers with lower SES origins via a newly-designed, scalable psychological intervention. I find evidence of its effectiveness in a 3-month longitudinal field experiment. Overall, the class ceiling can be partly addressed by changing the mind and empowering workers themselves.