The relationships among mastery and frequency ofmanagerial behaviors, and subunit effectiveness havefrequently been confused. This study investigates bothmain and interactive effects. The results show that the interaction effect can often be thestrongest effect and that increasing frequency withoutimproving mastery can sometimes be detrimental.Furthermore, these results offer a possible explanation as to why research of managerial behavior hasbeen so inconclusive. In addition, the results questionpopular advice given often to managers. Finally, somerecommendations are made as to how management development could be made more effective basedon the results of this study.