Critical thinking is a key element of complex problem-solving that facilitates health professionals’ clinical practice and professional behavior. Despite the importance of critical thinking, the measurement of critical thinking skills and its associations with academic performance remains a challenge. The aim of this study was to determine the associations between critical thinking and academic performance among undergraduate dental hygiene students. All 63 third- and fourth-year baccalaureate degree dental hygiene students (Class of 2018 and Class of 2017, respectively) in The Ohio State University Dental Hygiene Program were invited to participate in this quantitative, cross-sectional research study. Critical thinking was measured with the California Critical Thinking Disposition Inventory (CCTDI) and the Health Sciences Reasoning Test with Numeracy (HSRT-N). A total of 45 students completed the two tests, for an overall response rate of 71.4%. For the Class of 2018, the response rate was 90.6% (n=29), and for the Class of 2017, the response rate was 51.6% (n=16). The results showed the CCTDI and HSRT-N scores were higher for the Class of 2017 than the Class of 2018, suggesting that critical thinking skills were being developed across the course of the curriculum. The CCTDI was not significantly correlated with or a predictor of academic performance. The HSRT-N was more correlated with clinical performance than was the CCTDI, and HSRT-N components were found to be predictors of clinical performance. Continued attention is needed in the development and measurement of critical thinking skills to improve the academic and clinical performance of undergraduate dental hygiene students.