This paper applies semiparametric regression models using penalized splines to investigate the profile of well-being over the life span. Using data from the British Household Panel Survey (BHPS) and the German Socio-Economic Panel Study (SOEP), the analysis shows a common, and quite similar, age-specific pattern of life satisfaction for both Britain and Germany that can be characterized by three age stages. The evidence suggests that the U-shaped profile is a good approximation of decreasing and increasing well-being in the first and second stage. After people reached their late 60s, however, a decline in well-being is found in the third stage.