For most nonprofit organizations (NPOs) the procurement of donations is the core function of nonprofit marketing efforts (Bennet 2019). As NPOs are facing increasing competition (McKeever 2018; Bennet and Sargeant 2005) and a decline in number of donors in several OECD countries (Giving USA 2019; Jarvis 2019; GfK 2018; QUT 2016), NPOs have begun to engage in online fundraising to approach especially younger donors (Aldridge and Fowles 2013). Research has already shown that social information about others’ donation behavior can positively affect donation rates in public solicitation settings. To date, similar experiments in online environments are lacking but are particularly worth studying as theories suggest a malfunction of descriptive normative information in anonymous donation calls (Van Teunenbroek et al. 2019). Based on the assumptions that (1) anonymity weakens social pressure and that (2) anonymity gives relatively more explanatory power to altruistic considerations, it can be hypothesized that the positive effect of descriptive normative information should be at least weakened. This hypothesis was tested in an online experiment (n=392). Results indicate not only a weakened but even reversed effect of descriptive normative information on the overall decision to donate on both group level (donation rate) and individual level (donation likelihood).