This longitudinal study examined associations between perceptions of partner responsiveness and relationship satisfaction of each partner (new parents) across the first 2 years of a chronically stressful life event-the transition to parenthood. Responsiveness indexes the degree to which partners respond to each other with understanding, validation, and care. Consistent with prior work, lower ratings of responsiveness receipt and provision predicted declines in relationship satisfaction across the transition. These effects, however, were moderated by parental stress, such that among new parents who reported experiencing higher levels of parental stress, providing higher levels of responsiveness to partners was associated with declines in relationship satisfaction. Conversely, under lower stress, relationship satisfaction benefited from higher levels of both providing and receiving responsiveness. All of these effects held when controlling for both partners' levels of agreeableness, neuroticism, support-seeking, income, and work-family conflict. Post hoc moderation analyses revealed that high stress partners who reported providing higher responsiveness reported larger declines in relationship satisfaction if they scored higher in attachment avoidance or had more negative social exchanges with their partner. We discuss these novel stress moderation results in light of the need to and meaning of engaging in responsiveness, especially during chronically stressful periods of life. (PsycInfo Database Record (c) 2022 APA, all rights reserved).