The aim of this study was to assess the pattern of mutual relations within the Problematic Smartphone Use (PSU) (first network) and between adolescent mental health problems and PSU (second network). The invariance of both networks was investigated across age, gender, and severity of symptoms. The participants were 708 Romanian adolescents (M[subscript age] = 16). Analyses were performed in RStudio. The results indicated that the most central node in the PSU network was a preoccupation symptom. The strongest bridge path laid between a reckless symptom and PSU. The networks were invariant with respect to the gender of the adolescents but were different--both in structure and strength--between the adolescents with low vs. high total difficulties. Furthermore, the networks were significantly different in terms of structure between middle and late adolescents. These findings are further discussed.