This paper argues the relevance of analysing the origins of contextual effects to explain subjective well-being (SWB). Using the 2012 European Social Survey, the study applies social capital indicators to distinguish between-context and between-individual heterogeneity in three multilevel models of happiness and life satisfaction. Five indicators of social capital at individual and regional level are used to measure the trust, networks and norms dimensions of social capital. Random intercept and random slope hierarchical models are used to control for unexplained regional variability. The possibility of aggregated subjective perceptions conditioning, or interacting with, the effects of individual perceptions is also examined. The results show that the regional means of the social capital indicators are useful in explaining not only average levels of SWB (between-context heterogeneity) but also differences in the importance individuals attribute to their social capital (between-individual heterogeneity). The paper also proposes a research agenda to expand the frontier on contextual effects in the new science of well-being.