To promote psychological help-seeking, researchers have studied interventions to reduce self-stigma, a personally held belief that seeking psychological help would make one undesirable and socially unacceptable. We examined the differential impact of individual- and group-level changes in self-stigma on psychological help-seeking attitudes using data from 189 college students nested within 20 sections of a semester-long helping skills lab groups. We applied multi-level polynomial regression and response surface analysis to determine whether discrepancy between pre- and posttest self-stigma scores (i.e., reduction in self-stigma) predicted change in attitudes at the individual- and section-levels. Individual reduction in self-stigma did not predict psychological help-seeking attitudes but students who maintained consistently low to moderate levels of self-stigma throughout the course developed significantly more positive attitude toward psychological help-seeking. On the other hand, we found that greater section level reductions in self-stigma significantly predicted more positive psychological help-seeking attitudes, suggesting potential importance of group norm changes and effects in modifications of individual attitudes. Implications for research and stigma reduction strategies are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).