Previous research has distinguished between two types of working hard: workaholism, a “bad” type of working hard, and work engagement, a “good” type of working hard. However, the motivations underlying workaholism and work engagement have not been examined extensively. Building on Deci and Ryan's Self-Determination Theory, the present study examined the motivational correlates of workaholism, work engagement, and burnout (a possible consequence of working hard), using data from Chinese health care professionals (544 nurses and 216 physicians), and controlling for job demands and resources. As expected, structural equation modeling revealed that high levels of workaholism were associated with high levels of introjected regulation and identified regulation; that high levels of work engagement were mainly associated with high levels of intrinsic regulation; and that high levels of burnout were mainly associated with low levels of intrinsic regulation. Thus, different types of motivational regulation are associated with different types of job-related well-being.