In recent years there has been progressive recognition that individuals' self-perceptions of their wellbeing usefully complement objective welfare indicators. Wellbeing in relation to work, captured by self-reported job satisfaction, has not been an exception. However, job satisfaction evaluations depend not only on the objective circumstances workers experience in their jobs, but also on their subjective dispositions, such as their aspirations, expectations or personal evaluation criteria. We use matched employer-employee data from the UK and a within job modelling strategy to unveil whether and how subjective dispositions influencing job satisfaction vary across workers with different socio-demographic characteristics. We find that personal characteristics matter substantially more than job characteristics in determining job satisfaction, and that workers from disadvantaged collectives (i.e. female, very old or very young, non-white, homosexual or non-degree-educated) report higher satisfaction with the same jobs than those from advantaged collectives (i.e. male, middle-aged, non-white, heterosexual or non-degreeeducated).