["Aggressive Behavior, Volume 52, Issue 3, May 2026. ", "\nABSTRACT\nBullying during adolescence implies different forms of involvement that shape specific profiles, whose identification allows for understanding this phenomenon. However, it is essential to explore the mechanisms associated with the persistence or change of these profiles over time. Co‐rumination may be crucial as a social‐cognitive process in bullying development, reinforcing negative thought patterns among peers. The aim of this study was to examine involvement in bullying by identifying participation profiles and analyzing their longitudinal probability of stability or transition according to adolescents' levels of co‐rumination. A total of 1537 adolescents aged 12–16 years (54% boys and 46% girls; MAgeT1 = 12.98, SD = 0.82) participated at two time points 1 year apart. The latent profile analysis conducted with Mplus 8.10 identified three bullying profiles: bully‐victims, victims, and uninvolved, which showed stability across both time points. There was a tendency for bully‐victims and victims to transition toward the uninvolved profile, although bully‐victims also showed some probability of subsequently adopting the victim role. When considering co‐rumination, adolescents with higher levels were more likely to belong to the victim profile across both assessments. Regarding transitions, the findings revealed that an increase in co‐rumination was associated with a higher probability that victims maintain this profile, as well as with the transition of bully‐victims toward victimization. These results provide a deeper understanding of the evolving dynamics of bullying profiles and offer valuable insights for designing interventions aimed at promoting effective coping strategies.\n"]