Introduction: Intrafamily relationships are conceptualized as unity, support and emotional expression, as well as perception of difficulties that may arise in a family. Concurrently, internal and external strengths are key resources that promote positive adolescent development. External strengths are rooted in interactions with adults and institutions, while internal strengths are personal competencies developed through experience. Despite their importance, few studies have examined the relationship between these constructs in Latin American contexts. Aim: To assess the predictive influence of intrafamily relationships on strengths in Mexican adolescents. Method: A cross-sectional explanatory study using latent variables was conducted with 315 high school students in Mexico. Participants completed the brief reviewed version of the Intrafamily Relationships Assessment Scale and the reviewed version of the Internal and External Strengths for Teenagers. Separate structural equation models were tested for external and internal strengths. Results: The model for external strengths demonstrated an excellent fit: X2/gl = 1.40, CFI = .966, SRMR = .043, RMSEA = .036 [.031, .041]. Union, support, and expression strongly predicted maternal support (β = .73***), and paternal support/supervision (β = .62***). Conversely, the perception of difficulties predicted maternal supervision (β = -.38***) and friends without risky behaviors (β = .58***). The internal strengths model also showed a strong fit: X2/gl = 1.43, CFI = .961, SRMR = .050, RMSEA = .037 [.032, .042]. In this model, union, support, and expression predicted resistance to pressure (β = .64***), and the importance of health (β = .31**), while difficulties predicted resistance to pressure (β = .83***), and importance of religion (β = .20*). Discussion: The dimensions of intrafamily relationships predicted different strengths in adolescents. These findings highlight specific pathways that should be considered in comprehensive interventions aimed at strengthening students and their families.