Objectives The present study was aims to investigating the derivers, behaviors, and consequences of the fear of missing out (FOMO) in Iranian youth.
Methods This is qualitative study using the grounded theory. Participants were 21 young adults with FOMO aged 18-25 in Mashhad, Iran. Sampling was done using a purposeful sampling method until reaching data saturation. Przybylski’s FOMO scale was used to diagnose FOMO in samples. Unstructured in-depth interviews were conducted to collect data. In addition, semi-structured interviews with experts were conducted for data richness. 
Results We extracted one central theme “trying to achieve self-adequacy” and eight main themes including inadequacy of the family, personal factors, biosocial challenges, perpetuating factors, resulting failures, short-term successes, drowning in FOMO, and rescue from FOMO.
Conclusion The FOMO in Iranian youth originates from their lack of self-adequacy. It is necessary to pay attention to and strengthen the sense of self-adequacy in young adults to prevent the development of FOMO.