Across nearly all cultures, sharing a lifelong committed relationship with an intimate partner comprises an almost universal and strongly held ambition. Nevertheless, cross-national data reliably indicate a high prevalence of relationship distress and dissolution, with adverse emotional and physical health consequences for adult partners and their children. This introduction to the special section summarizes findings regarding the effectiveness of couple therapy for treating general relationship distress, couple-based interventions for individual mental or physical health problems, and couple relationship education programs aimed at helping couples sustain a healthy committed relationship. Within each of these approaches, evidence regarding potential mediators of interventions' effectiveness is reviewed, and critical unanswered questions are highlighted. Discussion concludes with a brief introduction to each of the articles comprising this special section on universal processes in couple therapy and relationship education.