Marital and family research has tended to focus on distressed relationships. Reasons for this focus are documented before keys to establishing a positive relationship science are outlined. Increased study of positive affect is needed to better understand relationships, and the best way to accomplish this goal is to embrace the construct of “relationship flourishing.” The behavioral approach system and the behavioral inhibition system are described and their potential role in understanding positive relationship processes is described using, as examples, commitment and forgiveness. A link to positive psychology is made, and it is proposed that the study of positive relationships constitutes the fourth pillar of this subdiscipline. Finally, the potential for focus on positive relationship processes to integrate multiple literatures is noted.