The power to control decisions is rarely distributed equally in committees. In a small voting committee, in which members have conflicting interests, we study how the decision right to break ties (formal power) translates into effective control over outcomes (real power). Two controlled experiments show that the level of real power held by the chair is larger than predicted by rational-choice theory. We also provide causal evidence that the legitimacy, but not the salience, of holding formal tie-breaking power affects voting behavior and thus the distribution of real power in the committee. Attitudinal measures related to the perceived attractiveness of the decision right to break ties exhibit a strong asymmetry between the one holding the decision right and those who do not.