This Article analyzes the possible antitrust liability of medical credentialing programs by dividing their potentially anticompetitive acts into three categories: (1) communicative behavior—for example, credentialing agencies’ promulgation of standards—designed primarily to influence government decision making; (2) communicative behavior designed to influence private decision makers, such as consumers, hospitals, and training programs; and (3) noncommunicative behavior—for example, an agreement by the credentialing agency and others to boycott a group of professionals—that might be used to exclude competitors from various fields of medical care. The author argues that the first amendment of the U.S. Constitution, together with the related Noerr-Pennington doctrine, should exempt from antitrust law any credentialing standard that has been adopted for a good-faith purpose and is at least arguably reasonable. On the other hand, the author also argues that antitrust law should condemn any “sham” standard that in fact is designed to eliminate or to punish competitors, and any other noncommunicative behavior by credentialing agencies for the same purpose.