This study aimed to explore the effects of mattering, social media addiction, online activity, school connectedness, age, and gender on anxiety/depressive symptomatology among U.S. adolescents. A nationally representative Qualtrics panel sample consisting of 441 adolescents (M[subscript age] = 17.3; SD[subscript age] = 1.67) participated in this study. The results of a three-step hierarchical multiple regression analysis indicated that gender, social media usage, and mattering were most strongly associated with adolescent distress (i.e., anxiety/depressive symptom reporting). For the full predictive model with all six predictors added, mattering was found to significantly improve the prediction of adolescents' anxiety/depressive symptomatology, contributing an additional 12.8% of explained variance. For this sample, adolescent girls participants reported experiencing more anxiety/depressive symptoms. Furthermore, higher levels of social media usage, indicative of an addictive stage, and lower levels of mattering were related to more significant anxiety/depressive symptomatology. Overall, mattering was found to significantly correlate with adolescent distress, online activity, problematic social media usage, and school connectedness, evidencing its importance in addressing adolescent mental health.