Background: Problematic Internet Use (PIU), as well as Problematic Facebook Use (PFU), is a growing concern worldwide. Like Facebook, Twitter is a widely used social networking site. Yet, no study has been conducted on the specific problematic Twitter use (PTU). Objectives: The main goal of this study was to explore the rate of problematic Twitter and Facebook uses, their relationships and differences in terms of psychopathological and internet-related variables. Patients and Methods: A sample of 822 Facebook users (55% women) aged from 18 to 29 (Mean = 21.6; SD = 2.8) completed a set of questionnaires assessing Twitter, Facebook, and the internet use characteristics and problematic uses, as well as psychopathological symptoms. Results: Among the total sample, approximately 18% of the participants had a PIU. Besides, more than 4% (n = 34) had a PFU with a significantly higher rate of women (P < 0.01). Twitter users were represented by approximately 32% (n = 259) of the sample. 21% (n = 55) reported a PIU, 3.1% (n = 8) a PTU (n = 8), and 3.9% (n = 10) a PFU with a significant majority of women (P < 0.05). Multiple-regression analysis revealed significant differences between PTU and PFU, particularly in terms of time spent on Facebook and psychopathological symptoms. Conclusions: PFU was particularly related to depression and anxiety symptoms while PTU was not. Moreover, our results suggest further exploring the specificity of specific Social Networking Site (SNS) instead of encompassing them into a general problematic use of the internet or SNS. This exploratory study had limitations and needs to be completed by research focusing on relationships and differences between these uses. Future studies need to focus on the relationship between problematic SNS uses, taken separately, with psychopathology, and especially pathological personality traits, by taking gender into account.