--- - |2 The purpose of this study was to assess the longitudinal association between adolescent dating relationship dynamics (measures of intimacy and problem dynamics), mental health, and physical and/or sexual victimization by a dating partner. Gender‐stratified analyses were conducted in a sample of 261 adolescents, ages 10–18 at baseline, interviewed in three annual waves (2013–2015) of the nationally representative Survey on Teen Relationships and Intimate Violence (STRiV). Among male daters, better mental health at baseline was negatively associated with problem dynamics at follow‐up, and aspects of problem dynamics at baseline predicted worse mental health at follow‐up. However, unexpectedly, aspects of relationship intimacy at baseline were also negatively associated with mental health at follow‐up. Male daters’ victimization did not mediate longitudinal measures of mental health or of relationship dynamics, but did predict worse mental health at follow‐up. Among female daters, we found no longitudinal associations between mental health and intimacy or problem relationship dynamics, in either direction. However, victimization mediated aspects of female daters’ reported relationship dynamics. Dating violence prevention efforts should reflect that adolescent females reporting controlling behaviors and feelings of passionate love may be at increased risk for victimization. Positive youth development efforts should attend to the bidirectional associations of mental health and dating relationship dynamics over time, particularly for male adolescents. - Journal of Research on Adolescence, EarlyView.