Objective: To develop a deeper understanding of how jealousy escalates to physical dating violence within Mexican American adolescent romantic relationships. Method: Using grounded theory, 20 focus groups of self-identified Mexican American adolescents (N = 64; 15–17 years old) were analyzed by level of acculturation and gender. Results: Three distinct “jealous” typologies resulting in dating violence were identified: normative jealousy (typically highly acculturated or bicultural male and female adolescents), jealous and possessive (typically bicultural male adolescents), and jealous and accepting of dating violence norms (typically low acculturated male adolescents). Across types, jealousy was upheld within a peer culture that constructed loose definitions of cheating behavior and was identified as the most salient relationship issue that held the potential to escalate to extreme forms of anger and resulting violence. Conclusions: Adolescents’ behaviors within their romantic relationships are embedded within a peer environment that legitimizes and fosters relationship jealousy. Jealousy is a particularly salient and troublesome relationship issue among acculturating Mexican American adolescents, who struggle as it is normatively experienced yet initiates processes leading to partner violence. Dating violence preventative interventions need to target both culturally influenced intrapersonal factors (e.g., communication and anger management skills, acceptance of dating violence) as well as peer norms (e.g., partner monitoring) to effect change among Mexican American youth. (PsycINFO Database Record (c) 2014 APA, all rights reserved)