This thesis examined happiness-enhancing behaviours using the framework provided by agency ("getting ahead') and communion ('getting along'). Agency entails a self-focused orientation and involves qualities such as ambition, independence, and competence. An example of an agency behaviour is, "strive to improve my skills". In comparison. communion entails an other-focused orientation and concerns connections with others, solidarity and co-operation. An example of a communion behaviour is, e.g., "spend quality time connecting with others", Three key research questions were addressed: (1) Are agency and communion behaviours beneficial for well-being? (2) Is a balance between agency and communion required for optimum well-being? (3) Are agency behaviours and communion behaviours beneficial for everyone or only for those who achieve a good person-activity fit, i.e., those whose traits fit with the behaviours? A series of studies were conducted involving correlational studies (Studies 1a to 4), naturalistic studies (Study 5, Chapter 6), and an intervention study (Study 6, Chapter 7). The findings revealed that agency and communion behaviours were positively related to and increased well-being. There was some support for the notion that a balance of agency and communion is needed for well-being. Specifically, analyses revealed that lower well-being was significantly associated with instances in which either dimension was so extreme it came at the cost of the other dimension (e.g., behaviour in which agency is performed at the cost of communion). Findings also showed that the co-occurrence of agency and communion in a single behaviour (referred to as a-c behaviour) was positively related to and increased well-being. With regard to person-activity fit, overall, the findings showed that the extent to which agency and communion behaviours were consistent with an individual's traits did not matter. However, the extent to which individuals perceived the behaviour as matching his or her traits did matter. Specifically, the more participants perceived the activity as matching a behaviour they were asked to enact, the more likely they were to experience gains in well-being. This thesis concludes with a discussion of the theoretical and applied implications of its findings and identifies some promising avenues for future research.EThOS - Electronic Theses Online ServiceGBUnited Kingdo