In a number of studies, researchers interested in positive organizational behavior have sought to better understand the favorable aspects of work engagement—a pervasive state of emotional attachment and motivation toward work. In this study, however, we investigate a potentially negative outcome of engagement. Drawing upon conservation of resources theory, we hypothesize that engagement will be associated with higher work interference with family due to the resources engaged employees may expend when they engage in extrarole work behavior such as organizational citizenship behaviors (OCBs). We further propose that conscientiousness, as a personal resource, serves to buffer the relationship between OCB and work interference with family. Examining multisource data, collected at multiple points in time, from 3 diverse samples (total N= 844), we find that state engagement is associated with higher levels of work interference with family and that this relationship is mediated by the performance of OCBs. The findings also indicate that engaged employees who are highly conscientious experience lower levels of work interference with family than engaged employees who are less conscientious. The implications of our study and directions for future research are also discussed.