This study examined whether violations of partner expectations-and attributions and perceptions of these violations-are associated with relationship satisfaction across the transition to parenthood. First-time parents (N = 99) mixed-sex couples completed mail-in packets during pregnancy (Time 1; T1) and when their babies were 3-5 months old (Time 2; T2). Hypotheses were largely confirmed. Multilevel modeling results indicated a significant T1-to-T2 decrease in relationship satisfaction. Expectation violations significantly predicted change in satisfaction; undermet expectations are associated with decreased satisfaction. T2 perception of expectation confirmation predicted change in satisfaction at T2 and moderated the relationship between expectation violation and relationship satisfaction. Likewise, benign postnatal attributions were significantly associated with the change in satisfaction at T2 and moderated the relationship between expectation violation and relationship satisfaction. Clinical and research implications are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).