The current study, using prospective data over 25 years (1991–2015; N = 245 couples), investigates life course dyadic patterns of positive and negative marital trajectories (i.e., marital strength and strain, respectively) in middle-aged husbands and wives and an array of physical and mental health outcomes associated with these patterns. Spousal warmth, spouse’s constructive conflict resolution, and couple’s joint participation were used as indicators of marital strength, whereas spousal hostility, spouse’s destructive conflict resolution, and marital instability were used as indicators of marital strain. Four dyadic latent classes with heterogeneous trajectory patterns were identified using husbands’ and wives’ concurrent strength and strain marital trajectories (1991–2001), including a couple stable and moderately favorable group, a couple stable and highly favorable group, a couple stable and husband more favorable than wife group, and a husband improving with wife slightly worsening group. The best health outcomes in 2015 were generally reported by members of the couple stable and highly favorable group, whereas the worst health outcomes were found, on average, for members of the husband improving with wife slightly worsening group. Based on these findings, interventions should promote and develop resiliency factors, thereby aiding in the redirection or improvement of middle-aged spouses’ marital trajectories, which can reduce detrimental positive–negative imbalances in marital strength and strain.