Emerging adulthood is a life stage with elevated risk for both mental disorders and financial distress. Although a positive link between financial stress and depressive symptoms has been identified, there is a lack of delineation on the temporal dynamics of this link spanning the entire stage of emerging adulthood (roughly ages 18 to 29). Using a statistical approach that partitions between-person from within-person variation and based on four waves of data from a college cohort (N = 2,098) throughout emerging adulthood, this study addresses this gap. Latent growth curve model analyses indicate that the trajectory of financial stress throughout emerging adulthood followed an inverted "U" shape, whereas that of depressive symptoms displayed a linear, decreasing trend. The positive correlations of both intercepts and slopes between financial stress and depressive symptoms indicated a co-development pattern. Classical, cross-lagged panel model analyses (i.e., a model aggregating between-person and within-person variation) demonstrated a reciprocal positive association between financial stress and depressive symptoms across waves. Random intercept, cross-lagged panel model analyses (i.e., a model disaggregating between-person and within-person effects) indicated a unidirectional positive within-person effect from depressive symptoms to financial stress across waves, controlling for between-person effects. Shared-method and shared-informant variance may inflate the identified associations, and the correlational data precludes casual inferences. Improving young adults' mental well-being, specifically intervening depressive symptoms, could be an avenue for reducing their financial stress. Future research is pressing to examine mechanisms via which depression symptoms manifest as financial stress during transition to adulthood. Copyright © 2020. Published by Elsevier B.V.