This article explores some weaknesses of existing approaches to defining "evangelical" for the purpose of quantitative identification, classification and comparison of evangelical organizations. It builds an argument for the necessity of a different way of looking at the definitional task. An approach to definition is described which is broad enough to encompass variations among organizations but can be applied narrowly to differentiate organizations from each other without excluding fringe organizations and without relying on sufficient or dominant characteristics. "Evangelical" as a descriptive characteristic is shown to be ambiguous but "evangelical" as a class of organizations sharing a limited number of necessary characteristics and a large number of general characteristics remains useful.