Today, practitioners often have to face a number of challenges during the standardization of business processes, and some processes can be standardized easier (with less effort) than others. Our previous research has shown that major drivers of successful business process standardization are the characteristics respectively the complexity of a particular business process. In order to minimize standardization effort, we need an instrument that allows identifying processes which are appropriate for standardization by assessing each process’ individual degree of complexity. On the way towards such an instrument, the first step is to develop an understanding of how the complexity of a business process affects its standardization. Therefore, the main aim of this paper is twofold: First, we provide a research model representing the fundamental relationships between our main constructs standardization effort, process complexity, and process standardization. Second, we report on the development of valid measurement scales designed to measure these constructs.