The rapid growth of Internet has resulted in the rise of WebQuest learning recently. Teachers encourage students to participate in the searching for knowledge on different topics. When using WebQuest, students' self-regulation is often the key to successful learning. Therefore, this study establishes a self-regulated learning system to assist learners in employing WebQuest learning in a self-regulated learning pattern as well as to give teachers opportunities to monitor and assist students' performance. The participants in the study are sixth graders of an elementary school in Taipei County, Taiwan. The experimental group and the control group are composed of three classes respectively. The current study investigates the correlation between students' self-regulated behavior and their achievement when using WebQuest learning through the self-regulated learning assisted functions and traditional WebQuest learning. In addition, learners' self-regulated behavior is observed and analysed based on the system records as well as their behaviour in the learning process. (Contains 14 figures and 10 tables.)