This paper explores whether eclectic theory (principal-agent theory incorporating key insights of social exchange theory) leads to better predictions about internal control systems in corporations than does principal-agent theory. Eclectic theory is shown to be able to explain various 'puzzles' for principal-agent theory. Moreover, several predictions are tested on 1985 data on 116 executive board members of medium-sized Dutch firms. Consistent with predictions, the paper finds that when the principal is the board of directors or the CEO, monitoring is not the important control instrument suggested by principal-agent theory. When the principal is the CEO, such monitoring is in fact even detrimental.