The present investigation is framed in the field of cyberpsychology. It aimed to analyze the predictive power of variables related to the use of social media sites --SMSs-- (i. e., connection time, type of use --passive / active--, motivations for use) and social comparison, on perceived psychological distress (i. e., depression, anxiety, stress). Furthermore, the mediating role of social comparison in the relationship between the passive use of SMSs and the perceived psychological distress, was also analyzed. It is important to study these topics since different international studies have shown inconsistent and contradictory results regarding the effects of SMSs use on individuals' well-being (e. g., Frison y Eggermont, 2015; Kraut et al., 2002; Nie et al., 2015). Consequently, some studies have focused on understanding whether the manner in which people use the networks, whether actively or passively, explains how technology impacts on users' well-being and/or psychological distress (Verduyn et al., 2015). The negative impact of passive use of SMSs can be explained by the Social Comparison Theory (Festinger, 1954), which suggests that people tend to evaluate themselves in comparison with others. These comparisons might generate negative effects on the individual (Giagkou et al., 2018) and, according to Lup et al. (2015), social comparison may be a mediating variable in this association. Regarding participants of the study, a convenience sample of 420 subjects of general population was studied (211 men, 209 women). The mean age was 40.29 years old (SD = 14.93). The majority of the participants (n = 278) lived in Buenos Aires City and surroundings. In terms of variables related to the use of SMSs, when asked about type of SMSs, most participants reported using more than one SMS, mainly Facebook (72 %) and Instagram (57 %). Regarding time spent on SMSs, 60 % of the respondents used their favorite SMS more than three times a day. The mean daily time engaged on all the SMSs exceeded five hours. Data were gathered using the Motives for SMSs use Scale (Lupano Perugini y Castro Solano, 2021a), the Iowa-Netherlands Comparison Orientation Measure (INCOM-E) (Buunk et al., 2005; Gibbons y Buunk, 1999), the Depression, Anxiety and Stress Scale (DASS-21) (Antúnez y Vinet, 2012; Lovibond y Lovibond, 1995). Furthermore, a survey to assess individuals' use of social networks was designed. The first part explored the most frequently used SMSs, the number and type of friends/followers, and the time spent on SMSs. The main SMSs were listed and participants were asked to indicate whether they used them or not, and if they did, they rated the amount of time spent on SMSs daily. The total amount of time per day was also surveyed. The second part of the survey was designed based on The Passive Active Use Measure (PAUM, Gerson et al., 2017) and some users' suggestions. This instrument assesses the frequency of certain activities performed on the networks to find out if participants make active use (e. g., posting information, commenting) or passive use (e. g., viewing profiles and posts, scrolling). The obtained results showed that social comparison is the main predictor of psychological distress. The motivation for use related to pass time / exhibitionism was also a significant predictor. In addition, an indirect effect of passive use on perceived psychological distress could be verified, considering social comparison as a mediating variable. Therefore, using the social networks passively would generate greater discomfort if the user tends to compare themselves with those who make the publications. The results of this study allow both users and healthcare and education providers to have greater knowledge of the consequences of using social media on individuals' overall well-being, and to promote their proper use. [ABSTRACT FROM AUTHOR]