Goal 2 of the "APA Goals for Undergraduate Major in Psychology," Scientific Inquiry and Critical Thinking, addresses the development of scientific reasoning and problem-solving, including effective research methods, in undergraduate psychology students. These skills serve as the foundation of not only introductory courses but also the entire psychology curriculum. In this article, we address why these skills are critical to help students interpret information and assess claims and review the current practice of measuring student reasoning in this domain. The reach of Goal 2 is broad, including the application of scientific reasoning to interpret psychological phenomena, the demonstration of psychology information literacy, the interpretation and execution of basic psychological research, and an understanding of sociocultural influences in scientific inquiry. We discuss the value of both formative and summative assessments in this area, offer examples of assessment tools currently in use, and provide a list of nationally normed assessments in critical thinking and scientific reasoning. We conclude with a discussion of limitations in current assessment practices and suggest possible future directions.