Generalization on the basis of prior experience is a central feature of human and nonhuman behavior, and anomalies in generalization can give rise to a wide array of problems. For instance, elevated levels of generalization have been shown in individuals suffering from an anxiety disorder. Identifying the individual difference variables that influence the extent to which behavior generalizes to novel stimuli may help our understanding of generalization and its potential maladaptive consequences. In this study, we first present an index of generalization that captures individual differences in generalization in a single continuous measure, thereby surpassing problems associated with traditional analyzing techniques. Further, we investigate whether generalization is predicted by working memory capacity. More precisely, it is hypothesized that generalization is a function of individual differences in the capacity to compare the current situation with previous learning experiences in working memory, and to adjust subsequent behavior accordingly. In a community sample, we found higher levels of generalization in individuals who were less efficient at filtering out irrelevant information from access to working memory. These results suggest that working memory impairments may contribute to elevated and potentially maladaptive levels of generalization.