 This study found that certain characteristics of friendship networks were associated with physical activity and sedentary behavior among female university students. Specifically, being part of a cluster of friends was associated with increased physical activity while being popular was associated with decreased physical activity. Additionally, a 10 percentage point increase in active friends was associated with a higher probability of being physically active, while a 10 percentage point increase in the number of sedentary friends was associated with a higher probability of being sedentary. This article was authored by Carlos Mario Orango Patanena, Jason Cardona Gomez, Victor Hugo Arboleta-Serna, and others.