The OECD welfare states have gradually been evolving into social investment welfare states by shifting social policy focus beyond passive income compensation to more proactive risk prevention. Contemporary welfare research, however, lacks any assessment as to how social investments foster capabilities and improve subjective wellbeing in terms of people’s life-course aspirations across multifarious life-course and labour market transitions. In other words, the social investment literature has yet to take subjective wellbeing seriously. The central aim of this thesis is to provide empirical evidence and analysis on the relationship social investment policies and subjective wellbeing feedback. The conceptualization of wellbeing in the thesis is coined subjective capacity. It refers to the subjective experience of a person to function and achieve a fulfilling life worth living. Moreover, subjective capacity conjures up a wellbeing indicator more suitable to assess social investment than traditionally used subjective wellbeing indicators, such as happiness. Essentially, subjective capacity allows to investigate people’s evaluation of their capacity to function by investigating their agency, resilience, fulfilment of potential, and meaning. To explore subjective capacity returns on social investment, the empirical focus is on three important life-course stages that of parenthood, unemployment, and ageing. All three stages are crucial from a subjective wellbeing point of view as they pertain social risks for overall wellbeing. Moreover, family services, active labour market support, and active ageing policies are lynchpin social investment policies. The general assumption behind this thesis is that social investment adoption may alter the subjective capacity and appreciation in parenthood, unemployment, and ageing. The research effort embraces three methodological layers of, respectively, aggregate, crosssectional, and longitudinal analyses. The aggregate analysis is macro-level (correlational) launching pad for, next, a deeper cross-sectional investigation at the individual level, which, in turn, is complemented with a longitudinal analysis, allowing for improved contextualization on the more general findings macro-level correlations and crosssectional evidence. Thus, the focus on multiple life-course stages, operationalized through aggregate, cross-sectional, and longitudinal analyses allow the research effort to reach beyond simple correlations and to dive deeper into the effect of welfare provision on individual wellbeing across different life-course stages, both crosssectionally and longitudinally. The overriding research question is whether social investment policy provisions fulfil the promise of wellbeing. The findings of the study suggest that, for the most part, it does. The promise lives up particularly well in terms of parental and ageing individuals’ wellbeing. Subjective capacity of both parents and ageing individuals are positively moderated by social investment policy adoption. Subjective capacity of short- and long-term unemployed, however, does not seem to be moderated by social investment type policy adoption.