This paper addresses the question of how the adequacy of a person's employment status influences their health. We draw on and extend the Labor Utilization Framework to distinguish between different forms of underemployment (hours, income, skills, and status) and test their relative effects on a range of physical health and psychological well-being outcomes. Using data drawn from a nationally representative sample (N = 1,429) of adults of working age, we assess the concurrent effects of underemployment through a longitudinal design that controls for prior levels of health and well-being. The results indicate that underemployed workers do report lower levels of health and well-being than adequately employed workers. However, the relationship varies by both types of underemployment and indicator of health and well-being. We conclude by discussing future research to explore the relationship between underemployment and health and well-being.