Calls for educational reform in undergraduate STEM education have become more prominent in recent years, particularly in introductory/foundational courses. Such reform efforts were initiated 10 years ago in the general chemistry program at the University of Arizona. In this contribution, we describe the major successes and challenges encountered during the full implementation of a new chemical thinking curriculum across all sections of a large course serving thousands of science and engineering majors every year. Besides describing the goals and structure of the alternative curriculum, as well as its impact on student learning, our work seeks to provide insights into institutional conditions, resources, and constraints that foster or hinder the success of major educational reforms.