Young adulthood is a challenging life phase including major life transitions like leaving the parental home, finishing education, starting a first job, starting romantic relationships, and parenthood. These transitions are interrelated, and are likely to be influenced by earlier life experiences, such as childhood adversities and poor mental health. At the same time, young adults have to earn a living in a new world of work characterized by temporary employment, selfemployment, and a 24/7 work cycle in a global economy. To promote sustainable employment throughout the working lives of young adults, a life course perspective must be integrated into work and mental health research, policy, and practice. A life course perspective highlights the importance of prior life experiences, such as where individuals grew up, who they grew up with, and their education and health status prior to working. This chapter explains and emphasizes the importance of applying a life course perspective to the working lives of young adults.