In this article, a Theory of Emotional Capital is investigated, which stipulates that relationships are able to withstand threats when partners have built "emotional capital" within the relationship (by contributing to positive, shared experiences). Support for this idea was obtained in two studies using two samples (newlywed couples and more established married couples) and two methodologies (daily diary and observational methods). Both studies showed that individuals with high emotional capital were less reactive to relationship threats than those with low emotional capital. The importance of emotional capital for healthy and stable relationships is discussed.