The literature on managerial effectiveness has concentrated on cataloguing the administrative and interpersonal skills necessary for good management, yet has paid little attention to technical skill as a necessary skill at the lower levels of management. To date there is no empirical evidence directly linking technical skill to managerial effectiveness. This study thus tested three hypotheses: (a) technical skill provides incremental value over administrative and interpersonal skill in managerial effectiveness; (b) technical skill is related to social power and influence tactics; and (c) group autonomy significantly moderates the relationship between technical skill and expert power. One hundred seven first-level supervisors from local petrochemical and engineering companies completed an on-line survey, where they answered questions about their professional background and managerial skills; their respective subordinates and supervisors provided information about their technical skill, managerial effectiveness, power, and influence tactics habits. The hypotheses were partially supported; technical skill provided incremental value, and was related to power and influence tactics only when measured judgmentally. Possible explanations and future directions are discussed.