Objectives. To estimate social class inequities in US mortality using a relational measure based on power over productive property and workers' labor. Methods. We used nationally representative 1986-2018 National Health Interview Survey data with mortality follow-up through December 31, 2019 (n = 911 850). First, using business-ownership, occupational, and employment-status data, we classified respondents as incorporated business owners (IBOs), unincorporated business owners (UBOs), managers, workers, or not in the labor force (NLFs). Next, using inverse-probability-weighted survival curves, we estimated class mortality inequities overall, after subdividing workers by employment status and occupation, and by period, gender, race/ethnicity, and education. Results. UBOs, workers, and NLFs had, respectively, 6.3 (95% confidence interval [CI] = -8.1, -4.6), 6.6 (95% CI = -8.1, -5.0), and 19.4 (95% CI = -21.0, -17.7) per 100 lower 34-year survival rates than IBOs. Mortality risk was especially high for unemployed, blue-collar, and service workers. Inequities increased over time and were greater among male, racially minoritized, and less-educated respondents. Conclusions. We estimated considerable mortality inequities by class, gender, and race/ethnicity. We also estimated that class mortality inequities are increasing, threatening population health. Public Health Implications. Addressing class inequities likely requires structural, worker-empowering interventions. (Am J Public Health. 2023;113(6):637-646. https://doi.org/10.2105/AJPH.2023.307227).