Mastery-based testing (MBT) is a form of categorical grading where students are repeatedly assessed until they achieve a level of mastery. This paper describes the implementation of MBT in a university quantitative literacy class using a web-based homework system. Qualitative evidence in the form of student comments showed that quantitative literacy students preferred MBT because it reduced their stress levels and was perceived as substantially different from traditional assessment. Students' differentiation of assessments based solely on nomenclature was an unexpected and significant finding.