Nonprofit and Voluntary Sector Quarterly, Ahead of Print.
Voluntary contributions are a crucial resource for nonprofit organizations and challenging to acquire. Social information on other people’s contributions has been found to positively influence individual giving behavior. However, a clear understanding how social information reference groups impact volunteering intentions is missing. Drawing on social comparison theory, we conducted a survey experiment with variations in social information reference groups to shed light on mechanisms within social comparison processes in volunteering. Results show that volunteering intention increases when social information refers to reference groups similar to recipients (ingroups) compared with reference groups without similarities (outgroups). This effect is mediated by group identification. In contrast, shifts in volunteering aspiration are anchored by observed performance levels and independent of reference groups. The study contributes to the social information literature and suggests the need to distinguish different forms of social information to understand social comparison processes in volunteering, relevant for researchers and practitioners alike.