This thesis applies social psychological theories about intergroup relations (e.g., Social Identity Theory, Tajfel, 1981; the Intergroup Helping Relations as Status Relations model, Nadler, 2002) to investigate the process and outcomes of charitable giving. Moving beyond the traditional focus on studying donors, this thesis uses a mixed-methods approach (surveys, experiments, thematic analysis, and literature review) to show that charitable giving is triadic, relational, and contextualized. That is, decisions about donations are informed by a triad of actors (donors, beneficiaries, and fundraisers), the relationships between them, and the wider social context. Chapter 1 provides a general overview of previous scholarly work on charitable giving and key psychological theories identified as relevant to my approach. Findings from Chapters 2 and 3 confirm that beneficiaries affect donor choices and that the relationships (e.g., shared identities) between particular donors and particular beneficiaries are especially important. Chapter 2 comprises two surveys of confirmed (N = 675) and self-reported (N = 376) donors, which show that donors are not universally generous. Instead, consistent with the social identity approach (Tajfel, 1981; Turner, Hogg, Oakes, Reicher & Wetherell, 1987), donors prefer to support charities that align with their social groups in meaningful ways. Chapter 3 goes on to present thematic analyses of responses to the question of why donors support their favorite charity (N = 1,849 from 117 countries). Results show a self/other dichotomy in donor motivation: donors are more likely to reference the self when explaining giving to religious and research charities, but are more likely to reference the other (i.e., beneficiary) when explaining giving to social service, animal, or international charities. In combination, Chapters 4 and 5 demonstrate that social contexts affect charitable responses, in part by changing the perceived relations between donors and beneficiaries. Chapter 4 presents one survey (N = 189) and one experiment (N = 290) that show how government policy on foreign aid affects private giving by changing perceptions of national giving norms. Chapter 5 presents two experiments (combined N = 440) that demonstrate how political advocacy can affect charitable giving by changing donor emotions, perceptions of efficacy, and identification with beneficiaries. Chapter 6 highlights the importance of also considering fundraisers when studying charitable giving. Mediation analyses from two samples of peer-to-peer fundraisers (combined N = 1,647) show that when fundraisers identify more with their nominated charity they take more actions to raise money and that, in turn, results in more funds raised. In particular, results show that actions which make the fundraiser more salient (e.g., adding photos, sharing personal motivations) are most effective. Chapter 7 draws together evidence from my program of research and more than 300 articles from the interdisciplinary literature to generate a new model of charitable giving: the charitable triad. This model theorizes that charitable giving is informed by the dyadic and triadic relationships between donors, beneficiaries, and fundraisers as well as salient aspects of the wider social context. Finally, Chapter 8 draws the entire body of work together, discusses it in relation to previous research, and presents future directions for study. The program of research presented in this thesis demonstrates the triadic nature of giving, setting a new agenda for both future research on charitable giving and fundraising practice.