Purpose: This study examined how content knowledge (CK) varies between teachers with different levels of content expertise in teaching volleyball. In addition, it investigated changes to the content-experienced (C-Exd) teachers' enacted pedagogical content knowledge (PCK) and their students' performances after developing CK, compared with those of the content-expert (C-Ext) teachers. Method: Two C-Exd and two C-Ext teachers and their 72 students participated in this study. A well-designed CK workshop was implemented for the two C-Exd teachers' CK improvement. Differences in the teachers' CK, enacted PCK, and their students' performance measures were compared. Results: The results of this study indicated that the C-Ext teachers possessed stronger CK than the C-Exd teachers and that the C-Exd teachers improved their enacted PCK and the students' motor performance after the CK workshop without showing statistically significant differences from those of the C-Ext teachers. Conclusion: The study presents ways to promote teacher effectiveness with supportive evidence-based practices.