Young adulthood is characterized by an increased focus on serious, long-term relationships. Stressors such as negative communication within couples can impede the enactment of pro-social, relationship maintenance behaviors, which may be especially salient for Latinx young adults who place importance on personal relationships. Familism, a cultural value that emphasizes supportive bonds and a cognitive orientation towards maintaining relationships, may protect against negative communication by inspiring more prosocial responding. In a sample of 475 Latinx young adults (M = 24.8 years, SD = 3.22), I found that negative communication (e.g., partners' propensity to withdrawal or criticize during interactions) was inversely associated with individuals' own relationship maintenance enactment (e.g., affectionate and supportive efforts to sustain the relationship). However, familism buffered the association between negative communication and relationship maintenance; in instances of low familism, participants who observed more negative communication reported fewer relationship maintenance behaviors. Conversely, under conditions of high familism, the association between negative communication and relationship maintenance was no longer significant. Findings reinforce the negative effects of maladaptive communication in relationships more broadly and highlight the protective role of cultural values for Latinx relationships.