Temporary employees rank lower than permanent employees on various measures of mental and physical health, including well-being. Furthermore, much research has indicated an approximate U-shape pattern between age and well-being with a nadir in midlife. Temporary employment may well have different associations with well-being across the lifespan, likely harming people in midlife more than at the start of their working life. Using over twenty years of the German Socio-economic panel (SOEP), this investigation considers the relationship between temporary employment, age and well-being. The results show that temporary employment deepens the U-shape in midlife, and that this result holds when typical socioeconomic factors as well as the industry, region, cohort, personality, employment security and job worries are taken into account.