The aim of the present research was to advance an empirically- based and theoretically-meaningful framing of the fear of missing out phenomenon. To this end, we designed and conducted three studies. In the first, we developed a self-report assessment that measured the FoMO construct as an individual difference. In the second, we explored how fear of missing out constellates with a range of demographic and individual difference factors linked to social media engagement. In the third, we examined its emotional and behavioral correlates.