In this chapter, we review the most recent research on sacrifice in romantic relationships, emphasizing the crucial role that sacrifice plays in optimal relationship development and maintenance. Sacrifice is defined as forgoing immediate self-interest and incurring costs to the self—either by giving up something desirable, such as time or money, or by doing something undesirable—in order to benefit their romantic partner. We review research showing that the willingness to sacrifice can convey that partners are invested in and care about their relationships. We show that approach-motivated sacrifices often have positive consequences, whereas sacrifices made for avoidance motives often have negative consequences for both giver and recipient. Given that when partners make sacrifices for each other, they are likely to experience some negative emotions due to incurring personal costs, it is not beneficial to try to suppress or conceal these emotions from one’s partner, as suppression is associated with poorer relationship quality as reported by both members of the couple. We conclude the chapter by discussing future directions for research on sacrifice, including research on the temporal component of sacrifice as well as individual variation in how people make the decision to sacrifice for a romantic partner.