Background: The American Psychological Association (APA) has called on undergraduate psychology programs to embed training in ethics throughout their curricula. Although guidelines and resources exist, research on students' understanding of and ability to apply the discipline's ethical principles is limited. Objective: The purpose of this study was to learn more about psychology students' perceptions of their undergraduate training in ethics, understanding of what it means to behave ethically, and competence at applying ethical principles. Method: Forty-four psychology students rated their undergraduate coursework and fieldwork training in ethics, described what it means to be ethical, and proposed a department honor code. Responses were independently coded using a rubric based on APA's five ethical principles. Results: Participants reported that their undergraduate training gave them an adequate understanding of ethics. The majority included at least three ethical principles in their descriptions of ethical behavior but fewer than three principles in their proposed honor codes. Upper-level students rated their fieldwork training in ethics significantly higher than lower-level students. Participants with higher ratings of fieldwork training in ethics included significantly more ethical principles in their honor codes. Conclusion: Findings support APA's call to embed training on ethics throughout the undergraduate curriculum.