Reactance theory might be profitably applied to understanding failures in persuasive health communication but for one drawback: The developer of the theory contends that reactance cannot be measured. Rejecting this position, this paper develops four alternative conceptual perspectives on the nature of reactance ( i. e., combinations of cognition and affect), then provides an empirical test of each. Two parallel studies were conducted, one advocating flossing (N = 196), the other urging students to limit their alcohol intake (N = 200). In both cases, a composite index of anger and negative cognitions fully mediated the effects of threat-to-freedom and trait reactance on attitude and intention. The data showed that, in fact, reactance can be operationalized as a composite of self-report indices of anger and negative cognitions. The implications for persuasive communication, in general, are considered as well the specific findings for flossing and drinking.