Although research has explored the association between marital quality and physical health in marriage, existing research fails to consider possible bidirectional associations between changes in individuals' marital quality and self-rated health. To address this gap, this study used latent change models to assess whether adults' marital happiness and problems over a 20-year period predicted subsequent changes in self-rated health, as well as whether self-rated health over the same time period was associated with changes in marital happiness and problems. The sample included 707 continuously married adults who participated in all six waves of the Marital Instability Over the Life Course panel study. Participants averaged 35 years in age at the first wave and were continuously married to the same spouse over the 20-year period. Latent differential models in AMOS 19 showed that unidirectional coupling existed for marital happiness and self-rated health only, such that higher levels of marital happiness predicted subsequent elevations in self-rated health over time. No evidence was found for bidirectional coupling between marital problems and self-rated health. Possible explanations for these patterns of results are discussed, including important directions for future researchers. (PsycINFO Database Record (c) 2013 APA, all rights reserved).