Although bullying is increasingly researched in the USA, there remains a limited study of bullying among Mexican youth. To address this gap, the present study compared bullying dynamics across the two countries, with a specific focus on Latinx youth in the US and Mexican youth. Data come from a large school-based survey of 3030 US self-identified as Latinx/Hispanic and 2211 Mexican adolescents. The survey utilized the US-derived term Bbullying^for the definition-based questions with the definitions and behaviors translated into the local Mexican Spanish dialect. Logistic regression results indicated that the prevalence of youth who bully is similar; however, more Mexican youth reported being a victim while more US Latinx youth reported witnessing bullying. US Latinx youths' responses to bullying reflect behaviors emphasized in bullying prevention programs whereas Mexican youth reported more retaliatory responses. This study informs our understanding of similarities and differences in bullying dynamics across contexts, which is critical to informing intervention development and adaptation to target locally relevant bullying behaviors. Keywords Bullying. Bystander response. Cultural comparison. Victimization Bullying is a form of peer aggression in which a person is exposed, repeatedly and over time, to negative actions on the part of one or more other persons-typically in situations where there is a power or status difference between the victim and the perpetrator (Gladden et al. 2014; Olweus 1993). In addition to physically aggressive acts, bullying includes actions such as threatening, teasing, name calling, ignoring,