Indiana University - Purdue University - Indianapolis (IUPUI) / This philanthropic studies thesis aims to “increase the understanding of philanthropy, improve its practice, and enhance philanthropic participation” (Center on Philanthropy at Indiana University Overview) by studying the effects of social information, social norms and social identity on giving. It connects philanthropic studies research with theoretical developments in motivations for giving in economics, nonprofit management, nonprofit marketing, consumer behavior, and social psychology. It utilizes personal observations as well as quantitative methods including experiments and surveys on multiple samples including donors, undergraduate students and samples of the U.S. population. It generates actionable and efficacious knowledge to improve the practice of philanthropy. It contributes to the formation and growth of the young field called philanthropic studies - in theory, in methodology and in practice. This thesis includes five chapters. Chapter I will explain how the research question, philosophy and methodology are selected. This discussion will be for the entire thesis. Specific research questions, hypotheses, research designs, findings and implications will be explained in the subsequent chapters. Chapter II demonstrates the immediate and long-term effects of social information on donations and its boundary conditions in existing nonprofit donors in two field experiments. Chapter III shows that the psychological mechanism through which social information influences subsequent giving is perceived descriptive social norms in one field survey of donors and one laboratory experiment on undergraduate students. Chapter IV investigates how social identity congruency moderates the effect of social information on donations. It reports three field experiments on donors and samples of the general U.S. population and two laboratory experiments on undergraduate students. It shows that donors give more money to a public radio station if told that a previous donor with a similar identity also made a large contribution. This effect is more likely to occur when donors have high collective identity esteem and when attention is focused on others. Each chapter provides original fundraising techniques developed from these studies. Chapter V concludes with a discussion of the theoretical, methodological and practical contributions of this thesis and suggests directions for future research in philanthropic studies, and philanthropic psychology in particular.