Controversy surrounds the reciprocity between adolescent and parental depression. Limited studies rigorously tested the transactional model of depression from a family systems perspective considering the involvement of all family members, particularly in non-Western nations, using advanced modeling approaches that disentangle between- and within-unit (i.e., family) variances (e.g., random intercept cross-lagged panel model [RI-CLPM]). This population-based multi-informant longitudinal study applied RI-CLPM to evaluate the temporal dynamics of the interrelations among adolescent, maternal, and paternal depression in 1,733 Chinese families assessed biannually. Findings from two large independent samples (primary sample [N = 1,733]; replication sample [N = 989]) converged to suggest, in macro timescales: (a) more depressed parents-especially mothers-generally have more depressed adolescents (between-family associations); (b) a family member becoming more depressed than usual co-occurred with other members becoming more depressed than usual in the same wave (within-family cofluctuations), with the mother-adolescent dyads exhibiting greater concordance than the father-adolescent dyads; and (c) a family member becoming more depressed than usual did not prospectively predict other members becoming more depressed than usual (i.e., no within-family reciprocal effects). While patterns of cross-lagged effects were consistently null across contexts, cofluctuations were stronger in rural than urban families and stronger in families with older adolescents. Overall, findings suggest that in macro timescales, the previously identified associations between adolescent and parental depression likely occurred at the trait-like between-family level and state-like within-family cofluctuations. Future studies employing micro timescales (e.g., daily) can complement macro-timescale analysis to provide greater temporal resolution of the within-family interplays of affective symptoms between family members. (PsycInfo Database Record (c) 2024 APA, all rights reserved).