Social media are now an essential part of our everyday lives and people’s mental health has hence become a relevant collective issue. This research analyzes the relationship between social media usage and the psychological well-being of university students. It studies the relationship between their activity on Instagram and its effect on their mental health in terms of stress and certain underlying factors that may be contributing to this influence. This was undertaken using structural equation modeling of a sample of over 400 university students. We believe our study provides valuable information for present and future mental health care in this digital age.