A meta-analysis of 20 manuscripts reporting on 21 unique studies (N = 19,623) was conducted to investigate the magnitude of the association between adolescent romantic relationship quality (RRQ), romantic relationship breakups (RRB) and mental health outcomes (i.e., depression, suicide ideation, deliberate self-harm, and suicide attempt). Potential moderators of these relationships were also explored. The sample included U.S. and non-U.S. adolescents (13–17 years old), and young adults (18–29 years old). Results indicated statistically significant but modest relationships between both RRQ and RRB and mental health, with the first showing a stronger association. There was some evidence suggesting this relationship may be stronger for women, but no evidence it differed as a function of nationality or age. Additional research is needed to address the distinction between clinical and non-clinical populations on specific outcomes and to further explore the role of mental health outcomes as related to romantic relationship quality and breakups. Implications for practice include the need for (a) services to individuals emotionally affected by romantic relationships, (b) relationship quality psycho-education, and (c) screenings of individuals at risk due to low romantic relationship quality or recent relationship breakup.