Most prior studies of skill-based preventive interventions for couples compare changes in problem-solving behaviors made by treated couples with those made by control couples. Unexpected findings in these studies highlight the need to examine within-group variability in behavior change among treated couples, alternative behavioral domains, including dyadic support and coping, and partners' intended and actual use of strategies taught in the interventions. A 24-month longitudinal study of 109 couples participating in an 18-hour intervention designed to enhance communication and dyadic coping revealed that marital outcomes are enhanced to the extent that (a) wives increase their positive problem-solving behavior and husbands decrease their negative problem-solving behavior over the course of the intervention, and (b) wives and husbands increase their positive dyadic coping behaviors, and husbands decrease their negative dyadic coping behaviors. Moreover, greater postintervention use of strategies taught in the intervention program produced better outcomes, and wives' improvements in positive and negative dyadic coping strengthened associations between strategy use and relationship satisfaction. Discussion emphasizes the importance of devising interventions that target key interpersonal processes and that motivate participants to display newly acquired behaviors.