Intercultural romantic relationships, in which partners have different cultural backgrounds, are increasingly common. Intercultural marriages, however, remain relatively rare, accounting for only 5% of all unions in Canada. Intercultural couples may face additional barriers in maintaining their relationships over time, including reconciling their cultural and couple identities (identity integration) and communicating effectively about cultural differences (cultural inclusion). Despite these challenges, intercultural relationships may also provide opportunities for self-expansion – novelty or growth as a result of the relationship or a partner’s culture. Across three studies we tested the prediction that self-expansion in intercultural relationships would be associated with higher relationship satisfaction and lower conflict through cultural integration processes. In Studies 1 and 2—a cross-sectional study of people in intercultural relationships (N=242) and a dyadic study of intercultural couples (N=312)—we found that self-expansion (both in general, and specific to partners’ cultures) was associated with higher relationship quality through greater integration and cultural inclusion. In Study 3—a pre-registered experimental study (N=342)–we found that although people in a cultural self-expansion group reported higher relationship satisfaction compared to a control group, cultural integration processes did not mediate this relationship. Our findings reveal that sharing cultural differences and novel experiences can be beneficial for intercultural couples, extending self-expansion theory to intercultural relationships and providing insight into the maintenance of satisfaction over time.