Using data from the FFCW (n = 1,492 couples), the authors assessed stress, health selection, and couple-crossover hypotheses by examining (1) the bidirectional association between economic hardship and depressive symptoms one, three, and five years after the birth of a child; (2) the association between economic hardship and depression on relationship distress for both parents; and (3) whether the associations vary by marital status. The results suggest a pernicious cycle for mothers after the birth of a child. Economic hardship increases depression, but maternal depression also increases economic hardship. These reinforcing mechanisms increase both mothers’ and fathers’ relationship distress. Taken together, policies aimed at strengthening couples’ relationships should work in tandem with economic and mental health policies to reach optimal outcomes for couples with young children. Effect patterns were generally consistent between married and cohabiting couples, with some variation in levels of statistical significance.