The purpose of the study is to explore three kinds of personal affective traits among high-school students and their effects on web-based concept learning. The affective traits include personal preferences about web-based learning environments, personal epistemological beliefs, and beliefs about web-based learning. One hundred 11th graders participated in the study. Three questionnaires were developed to assess these affective characteristics. An online test and the flow-map technique were employed to probe concept achievements that indicated the learning outcome. Descriptive statistics, t-tests, correlation and regression analyses were conducted to present trends and relations among variables. It was found that participants of the study who mostly had not developed sophisticated epistemological beliefs displayed only moderate preferences toward explorative and interactive web-based learning environments, and they seemed to be conservative about the effectiveness of the new type of learning. According to the flow-map technique, the serial form of concept achievements was the main product of concept learning in the explorative web-based environments defined in the study. Regression analyses indicated that while preferences toward inquiry-based instructional designs and outward interactions, and the simple form of personal epistemology predicted concept achievements, beliefs about effectiveness of web-based learning resulted in a negative impact on concept learning. (Contains 9 tables and 2 figures.)