Course-based undergraduate research experiences (CUREs) and inquiry-based curricula both expose students to the scientific process. CUREs additionally engage students in novel and scientifically relevant research, with the intention of providing an "authentic" research experience. However, we have little understanding of which course design elements impact students' beliefs that they are experiencing "authentic" research. We designed a study to explore introductory biology students' perceptions of research authenticity in CURE and inquiry classes. Using the Laboratory Course Assessment Survey, we found that students in CURE sections perceived higher levels of authentic research elements than students in inquiry-based sections. To identify specific factors that impact perceptions of research authenticity, we administered weekly reflection questions to CURE students. Coding of reflection responses revealed that experiences of failure, iteration, using scientific practices, and the relevant discoveries in their projects enhanced students' perceived authenticity of their research experiences. Although failure and iteration can occur in both CUREs and inquiry-based curricula, our findings indicate these experiences--in conjunction with the Relevant Discovery element of a CURE--may be particularly powerful in enhancing student perceptions of research authenticity in a CURE.