Concurrent sexual partnerships are hypothesized to be a contributing factor to Malawi’s HIV epidemic. As social norms influence health behavior and have been found to influence sexual behavior, the purpose of this study was to explore two types of norms, descriptive and injunctive norms, toward concurrent sexual partnerships in Malawi. Data from 40 focus group discussions and 20 in-depth interviews conducted in five districts in Malawi, which included 318 participants aged 18–55 years, were analyzed. Participants perceived that concurrent sexual partnerships were extremely common, and believed that very few individuals in their communities were not in concurrent sexual partnerships. However, participants perceived that others in their communities heavily disapproved of concurrent sexual partnerships outside of polygamy, as polygamy was viewed as an acceptable type of partnership because it was conducted in the open. Participants asserted that there were no traditional practices that promoted concurrent sexual partnerships, and perceived that those that engaged in the behavior were for the most part stigmatized by community members. Further research is needed to obtain a thorough understanding of the way in which the perceived actions and beliefs of peers influence the beliefs, feelings and actions of individuals to strengthen HIV programming efforts in the region.