The authors developed and assessed a new undergraduate psychology course: Thinking and Writing in Psychology. A description of how the course was developed using the APA learning goals as well as results from an analysis of the course's effectiveness are offered. The course demonstrated a positive impact on the overall grade point average and thinking and writing skills of students within the course as well as in more advanced courses. Implementing and requiring a thinking and writing course relatively early in the undergraduate psychology major was strongly supported by this study. (Contains 2 tables.)