Objectives: Fear-of-missing-out (FOMO) refers to feelings of anxiety that arise from the realization that you may be missing out on rewarding experiences that others are having. Behavioral addiction researcher believe that FOMO is one process that may underlie problematic social media use (PSMU). This study explores the relationships between FOMO, the depth and breadth of social media use, the type of social media platform used, PSMU and phubbing behavior. Methods: An online survey was administered to 2663 school pupils. FOMO was measured using 4 items from Przybylski et al.’s (2013) FOMO-scale. PSMU was assessed using an adapted version of the C-VAT instrument; scale based on the CIUS-scale. Results: In line with our expectations, FOMO was a positive predictor of both the frequency (‘depth’) of teenagers’ social media use and the number of platforms (‘breadth’) that they use. FOMO was a stronger predictor of social media platforms that are less publicly accessible (e.g., Facebook, Snapchat) than platforms that are more public in nature (e.g., Twitter, Youtube). Moreover, FOMO is an important predictor of both PSMU and phubbing behavior. Conclusions: These findings support extant research that points toward FOMO as key driver for teenager’s social media use.