This article discusses the fear of missing out (FOMO) on rewarding experiences, an important psychological construct in contemporary times. We present an overview of the FOMO construct and its operational definition and measurement. Then, we review recent empirical research on FOMO’s relationship with levels of online social engagement, problematic technology and internet communication use, negative affectivity, and sociodemographic variables. Additionally, we discuss theoretical conceptualizations regarding possible causes of FOMO and how FOMO may drive problematic internet technology use. Finally, we discuss future directions for the empirical study of FOMO.