Web-based instruction is prevalent in educational settings. However, many issues still remain to be investigated. In particular, it is still open about how human factors influence learners' performance and perception in Web-based instruction. In this vein, the study presented in this chapter investigates this issue in a Web-based instructional program, which was applied to teach students how to use HyperText Markup Language (HTML) in a United Kingdom (UK) university. Sixty-one master's degree students participated in this study. There were a number of interesting findings. Students' task achievements were affected by the levels of their previous system experience. On the other hand, the Post-Test and Gain scores were positively influenced by their perceptions and attitudes toward the Web-based instructional program. The implications of these findings are discussed.