This study was conducted to explore the relationships between teachers' Internet self-efficacy, beliefs about web-based learning and attitudes toward web-based professional development. The sample of this study included 421 teachers, coming from 20 elementary schools in Taiwan. The three instruments used to assess teachers' Internet self-efficacy (ISS), beliefs about web-based learning (BWL), and attitudes toward web-based professional development (AWPD) revealed high reliability. In this study, the results supported that teachers' Internet self-efficacy and beliefs about web-based learning were important predictors of their attitudes toward web-based professional development. The belief for the positive consequences of web-based learning is very important for the favorable attitudes toward web-based professional development. (Contains 6 tables.)