Objective: Relationship education (RE) usually is conceived of as relationship enhancement for currently satisfied couples, with a goal of helping couples sustain satisfaction. However, RE also might be useful as a brief, indicated intervention for couples with low satisfaction. The current study evaluated the effect of RE on couples with low and high relationship satisfaction. Method: The study was a randomized controlled trial in which 182 couples were randomly assigned to: a book reading control condition (control); RELATE online assessment with feedback and relationship goal setting (RELATE); or RELATE with CoupleCARE (RCC), a flexible delivery skill-based education program. Couples were assessed on relationship satisfaction and individual mental health before and after RE, and through to 4-year follow-up. Results: Couples with high initial satisfaction showed no effects of RE on satisfaction. RCC but not RELATE increased satisfaction in couples with low initial satisfaction, but effects dissipated between 6 and 12 months after RE. There were no effects of RE on mental health. Conclusion: Flexible delivery RE produces immediate effects as an indicated early intervention for couples with low relationship satisfaction, but the effects attenuate. Future research needs to seek methods to produce better maintained effects.