AbstractThis study analyzes congruence and incongruence between mothers and adolescents on perceived maternal rejection as a predictor of externalizing and internalizing problems. The sample comprised 162 Spanish families (adolescent, father, and mother). The children (38.3% males, 98.8% Caucasian) were between the ages of 12 and 16 years old (M = 13.27, Sd = 1.23). Mothers and adolescents completed specific versions of the Parental Acceptance-Rejection Questionnaire, and fathers completed the Child Behavior Checklist. Polynomial regressions, including the quadratic and interaction terms of the predictors and response surface analysis, were conducted. The results indicate a congruent effect in predicting externalizing problems from mothers’ and adolescents’ reports on perceived maternal rejection. Thus, congruence between adolescents and mothers on high perceived maternal rejection is associated with the highest levels of adolescent psychological maladjustment, and congruence between adolescents and mothers on low perceived maternal rejection is associated with the lowest levels of adolescent psychological maladjustment. In contrast, the magnitude—but not the direction—of incongruence in perceptions between mothers and adolescents has a positive effect, as it is associated with a decreased risk of externalizing problems. This study contributes to existing knowledge surrounding the importance of employing multiple-informant assessment and using appropriate approaches to study discrepant reporting by mothers and adolescents on family variables, and its effect on adolescent mental health.