Perception of the need to be online can lead to the compulsive use of the Internet. The aim of this study is to investigate the relationships between Internet Addiction and Social Media Addiction and some psychological variables that could influence the onset of these disorders (FoMO, Emotional Dysre-gulation, Personality traits). The sample was composed by 598 Spanish university students aged from 18 to 35 (471 women and 118 men; average age = 21.56; standard deviation = 2.73). Participants responded to an online questionnaire regarding the use of Internet (IAT), the use of social media (BSMAS), Fear of Missing Out (FoMO), Emotional (Dys)regu-lation (DERS) and personality traits (BFI-15). Correlation analysis showed a positive relationship between FoMO, Social Media Addiction, Internet Addiction, Emotional (Dys)regulation and Neuroticism dimension of Big five. Also, we observed a negative relationship between Internet Addiction and Social Media Addiction, Conscien-tiousness dimension of Big Five, and gender. The tested mediation model highlighted that the total effect of the DERS on the IAT score was significant as well as its indirect effect via the BSMAS and FoMO scores was positive and significant. In conclusion, we proposed a new integrated model for understanding the characteristics, pre-dictors, and risk factors of IA.