Costs of employer-sponsored health care benefits have increased faster than workers' wages for several decades, with important implications for disparities in earnings and wage stagnation. To quantify how growth in employer-sponsored health insurance (ESI) premiums may have been associated with reduced annual wages, disparities in earnings by race and ethnicity and wage level, and wage stagnation among US families with ESI. In this economic evaluation, serial cross-sectional analyses were performed of US families receiving ESI from 1988 to 2019 based on data from the Consumer Expenditure Survey, Kaiser Employer Health Benefits Survey, US Census Bureau's Current Population Survey, and federal payroll taxation rates. Statistical analysis was conducted from February 2022 to July 2023. Percentage of annual compensation associated with health care premiums (after accounting for tax deductibility) and lost wages associated with growth in cost of premiums from 1989 to 2019 based on 1988 compensation. To assess disparities, analyses were stratified by race and ethnicity and wage level. In 1988, 44.7 million individuals (head of household: mean [SD] age, 43.3 [13.1] years; 30.1% were female; and 2.4% identified as Asian, 6.2% as Hispanic, 8.6% as non-Hispanic Black, and 82.8% as non-Hispanic White) were covered by ESI family plans; this number remained similar in 2019 at 44.8 million individuals (head of household: mean [SD] age, 47.1 [12.9] years; 41.3% were female; and 1.3% identified as Asian, 9.9% as Hispanic, 9.9% as non-Hispanic Black, and 78.9% as non-Hispanic White). In 1988, the mean (SD) household size was 3.3 (1.3) people, and in 2019, it was 3.4 (1.3) people. If ESI costs had remained at the same proportion of the 1988 average compensation package, then in 2019, the median US family with ESI could have earned $8774 (95% CI, $8354-$9195) more in annual wages. During all 32 years, health care premiums as a percentage of compensation were greater for non-Hispanic Black and Hispanic families than for non-Hispanic White families. By 2019, 13.8% (95% CI, 13.5%-14.1%) of compensation among non-Hispanic White families with ESI went to premium costs compared with 19.2% (95% CI, 18.8%-19.7%) among non-Hispanic Black families and 19.8% (19.3%-20.3%) among Hispanic families with ESI. In 2019, health care premiums as a percentage of compensation at the 95th percentile of earnings for families with ESI were 3.9% (95% CI, 3.8%-4.0%) compared with 28.5% (95% CI, 27.8%-29.2%) at the 20th percentile of earnings. From 1988 to 2019, the mean cumulative lost earnings associated with growth in health care premiums for the median US family with ESI was $125 340 (95% CI, $120 155-$130 525) in 2019 dollars, 4.7% of earnings over the 32-year period. This economic evaluation of US families receiving ESI suggests that 3 decades of increasing health care premiums were likely associated with reduced annual earnings and increased earnings inequality by race and ethnicity and wage level and were meaningfully associated with wage stagnation.