Cross-sectional evidence in the United States finds that informal caregivers have less attachment to the labor force. The causal mechanism is unclear: do children who work less become informal caregivers, or are children who become caregivers working less? Using longitudinal data from the Health and Retirement Study, we identify the relationship between informal care and work in the United States, both on the intensive and extensive margins, and examine wage effects. We control for time-invariant individual heterogeneity; rule out or control for endogeneity; examine effects for men and women separately; and analyze heterogeneous effects by task and intensity. We find modest decreases—2.4 percentage points—in the likelihood of working for male caregivers providing personal care. Female chore caregivers, meanwhile, are more likely to be retired. For female care providers who remain working, we find evidence that they decrease work by 3–10hours per week and face a 3 percent lower wage than non-caregivers. We find little effect of caregiving on working men's hours or wages. These estimates suggest that the opportunity costs to informal care providers are important to consider when making policy recommendations about the design and funding of public long-term care programs.