In this paper we re-examine the measurement of entrepreneurial activity and provide a model-based approach at measure. The Global Entrepreneurship Monitor (GEM) project has been a key addition to our ability to measure and compare rates of entrepreneurial activity. But even though there is consensus about the importance of measuring entrepreneurial activity, researchers differ about the appropriate ways to measure the breadth of entrepreneurial activity. We analyze the GEM's measure of entrepreneurial activity (TEA), address limitations in its design and development and provide an alternative measure of entrepreneurial activity, which includes entrepreneurial environment. We use a model-based approach to measure entrepreneurship activity and our results indicate that the model provides support for the combined use of entrepreneurial activity and entrepreneurial environment.