Objective: The objective was to examine mental health of undergraduate researchers (UGRs) during the COVID-19 pandemic. Participants: We surveyed 962 UGRs who were conducting research in Spring 2020 at over 100 US universities. Methods: We conducted an online survey in July 2020. We analyzed data using descriptive statistics and multivariable generalized estimating equations. Results: 63% reported at least mild anxiety and 73% reported at least mild depression based on GAD-7 and PHQ-9 scores; 15.2% reported severe anxiety (score [greater than or equal to] 15) and 23.4% reported severe depression (score [greater than or equal to] 15). More COVID-19-related adverse event experiences were associated with more severe anxiety and depression, as were first-generation status, woman gender, and LGBQ status. Greater social support was protective, and significantly more so for men (vs. women) and continuing generation (vs. first generation) students. Conclusion: Faculty have an important role in the mental health of their mentees. Additional interventions are needed to better support women and first-generation students.