This study analyzes the relationships between preservice teachers' technological pedagogical content knowledge (TPACK) and their self-efficacy beliefs in educational Internet use. Findings show statistically significant relationships among the knowledge domains in technology, pedagogy, content, and their intersections. Also, results from the canonical correlation analysis show that a statistically significant and strong relationship exists between the knowledge dimensions in the TPACK model and the self-efficacy beliefs in educational Internet use. Specifically, technology, content, and technological content knowledge domains are statistically significant predictors of preservice teachers' self-efficacy beliefs in educational Internet use.(Contains 3 tables.)