In response to the rising public and scholarly interest in understanding relational experiences in intercultural relationships, we propose a new concept—relational cultural intelligence (RCI)—to describe an individual’s ability to learn and apply cultural knowledge in intimate relationships. In this article, we outline the theoretical foundation of RCI, introduce the RCI scale, and present initial results on its reliability and validity. We conceptualize RCI as a type of social intelligence with three dimensions: awareness, skills, and knowledge. This study surveyed 186 individuals in the United States who identified as being currently in an intercultural romantic relationship. The results provide evidence for the reliability and validity of the three-factor scale with 12 items. Results also showed that RCI was related to important aspects of relational experiences, such as relational stress and relationship satisfaction, and that it explained variance in relationship satisfaction above and beyond relational stress, commitment, and relationship duration.