A tertiary course in Quantitative Reasoning (QR) has the potential to develop key practical and intellectual skills for citizenship, such as critical thinking, problem solving, quantitative literacy, and oral and written communication. In this article, we present research conducted on four instructors of such a QR course for students enrolled in a wide variety of nonscience degree programs at a university in the United States. The course used a student-inquiry approach to proportional reasoning, probability, statistical reasoning, and mathematical modeling. The findings are framed by a 5 C model of QR, which entails Critical thinking to link real-world Contexts to mathematical Concepts supported by student Collaboration and QR Competencies. The research addressed the questions of how university instructors support student development of the skills needed for critical citizenship and how this support relates to the 5 C model. We found that three of the four instructors viewed critical thinking as a central goal of the QR course and as supporting citizenship education. All four engaged students in tasks designed to develop a combination of skills associated citizenship, including critical thinking, self-questioning, collaboration, and communication. The discussion addresses such issues as the course’s merits and challenges, student engagement, the relative importance of the five Cs, the importance of instructional autonomy, and recommendations for related professional development and future research.