Most research in managerial effectiveness, or competence, focuses upon personal attributes of the individual. This understates the impact of context, which can assist or hinder job performance. A national (New Zealand) survey assessed the impact of 16 environmental variables, four management development variables and two variables reflecting personal skills and abilities, on the ability to be effective as a manager. Analysis revealed eight factors explaining the majority of perceived management effectiveness. The results suggest that support in a variety of forms is a key influence on the ability to be effective as a manager, with particular emphasis on the role of supervisors and subordinates, as well as organisational culture. Organisational level and organisational size interacted with contextual factors. The overall results suggest that, like other employees, managers are more likely to see both their success and hindrances as a function of their environment.