The concept of "moral exclusion" has often been used to understand harm-doing. The present studies examined two, distinct meanings that have been ascribed to this concept. First, exclusion has sometimes been conceptualized as the belief that moral principles do not apply to a target person or group (e.g., exclusion from the application of justice principles). Second, the term has been used to refer to exclusion from positive treatment that is accorded to others, which the actors believe to be morally justified, though outside observers do not. Distinguishing between these two meanings can clarify the mechanisms underlying the relation between proposed antecedents to exclusion and harm-doing. In two experiments, the authors obtained evidence compatible with each of these conceptualizations of exclusion, as well as preliminary evidence that certain antecedents are more likely to lead to processes indicative of one or the other conceptualization. The findings have practical implications for the reduction of harm-doing as well as for conflict that might arise in such attempts. (Published Abstract)