This paper was intended to investigate the effects of using e-books (or texts with multimedia support) in an extensive reading program (ERP) on EFL learners' attitudes toward reading in English. In a junior high school in northern Taiwan, 109 students from three intact classes were recruited in the ten-week ERP of e-books. Each class was introduced to a list of 140 selected e-books for the reading program; each student was then encouraged to read e-books after school, with the target of reading four e-books every week. The degree of changes in reading attitudes was assessed by using the reading attitudes scale (Stokmans, 1999) before and after the e-book ERP. In addition, the teacher's class notes of the students' reading behaviors and reactions as well as their spontaneous oral or written feedback were analyzed to be triangulated with the quantitative data. The results showed that the e-books had positive effects on the students' attitudinal changes in all dimensions of reading attitudes, namely, utility, development, enjoyment and escape, as well as in all the cognitive, affective and conative components. The results also showed that the features of the e-books, especially oral reading, highlighting, animations and music/sound effects, were considered important to change attitudes. The implementation of interaction and learner control in the e-books guaranteed positive attitudinal changes as well.