Purpose: The purpose of this study was to examine the efficacy of a content knowledge (CK) workshop on the enacted pedagogical content knowledge (PCK) of teachers and in turn the effects on student learning. Method: A quasiexperimental design was used to examine 4 questions: (a) How does student learning differ as a function of PCK? (b) How does teachers' selection of tasks differ in teaching as a function of CK? (c) How does teachers' representation of tasks differ in teaching as a function of CK? (d) How does teachers' adaptation of tasks differ in teaching as a function of CK? In examining student learning, 2 statistical analyses were employed using correct trials and incorrect trials as dependent measures, respectively. Analyses of variance were conducted examining the effects of the intervention on students' percentage of correct or incorrect trials. The analyses consisted of independent variables, including teachers as a block, treatment, class nested within conditions, gender, skill levels, and 2-way interactions among treatment conditions, gender, and skill levels. Results: A statistically significant effect was reported for both analyses. Effect sizes were 0.63 and 0.67, indicating a moderate-to-high practical difference between groups in favor of the experimental condition. Large effect size differences (>2.0) were found for teacher PCK behaviors. There were no interaction effects. Conclusion: Our findings show that the enacted PCK of a teacher can be changed from immature to mature as a function of learning CK and that this change has a significant and meaningful impact on student learning.