Adolescent psychopathological (i.e., internalizing and externalizing) symptoms are quite prevalent and decrease well-being in adulthood. Parental symptoms can put adolescents at risk for developing psychopathological symptoms. This study examined the reciprocal, longitudinal associations between parental and adolescent internalizing and externalizing symptoms between and within families, using random-intercept cross-lagged panel models (RI-CLPMs). Participants were 497 Dutch adolescents (43.1% girls; M[subscript age] T[subscript 1] = 13.0 years; mostly medium to high socioeconomic backgrounds) and their parents from the general population. Across six years, adolescents and their mothers and fathers reported annually on their internalizing and externalizing symptoms. Between families, maternal, but not paternal internalizing and externalizing symptoms were consistently associated with adolescent internalizing and externalizing symptoms, while within families, only increases in adolescent internalizing symptoms predicted subsequent increases in maternal internalizing symptoms. These findings suggest that associations within families differ from associations between families, and that within-family processes in the transmission of internalizing symptoms are particularly driven by adolescent-to-mother effects.