In this paper, we will describe the experience of the authors in using process-oriented guided inquiry learning (POGIL) in calculus at four institutions across the USA. We will briefly examine how POGIL compares to and fits in with other kinds of inquiry-based learning approaches. In particular, we will first discuss the unique structure of a POGIL activity, which includes a model and a learning cycle of specific types of questions. We then turn to a discussion of the particular characteristics of a classroom implementation of a POGIL activity, including facilitation strategies an instructor might use, the importance of specified student roles in groups, and different ways of reporting out. Finally, we provide some preliminary data on student pass rates in non-POGIL and POGIL calculus classrooms in the participating institutions. Throughout the paper, we use examples from student dialogues as groups were working through POGIL activities developed for Calculus I by the authors.