This study aimed to examine the common content knowledge (CCK) of tennis and volleyball among U.S. physical education PSTs at the time they entered their PETE program. A secondary purpose was to investigate the relationship between PSTs' CCK levels of volleyball and tennis when entering a PETE program. A total of 116 PSTs from seven universities in volleyball and 122 PSTs from eight universities in tennis participated in the study. The data sources included participants' demographic backgrounds and CCK assessments of volleyball and tennis. Descriptive statistics showed that PSTs' mean percentage of the correct scores for both volleyball and tennis CCK were below 45%. In addition, the linear regression analyses showed that university affiliation and playing experiences in volleyball accounted for 28.7% of CCK and university affiliation, sex, and playing experiences in tennis accounted for 22.2% of CCK. The findings of the study provide evidence to support the importance of teaching content knowledge in teacher education.