We explore the interplay between traditional evaluation criteria and social contagion in affecting investing behaviors and decisions of groups’ investors. Using in-depth data from a 26-month inductive field study of angel investing groups, we build a grounded model of underlying contagion effects on investing decisions. We ascertain three dimensions of a group’s credibility - collective analysis, collective fits, and professional structure, which encourage investors to appreciate gut feel and follow the earlier decisions of others. Moreover, our data suggest three factors – intrinsic quality, uncertainty, and personal traits – that moderate social contagion effects on investing behaviors and decisions.