Instructional innovation is a means of educational reform. Essential to instructional innovation are four factors; personnel related to the innovation-especially teachers and the principal, the degree and difficulty of the innovation, the measures and strategies the school, and the education authorities take, and the school and social context-especially their organizational culture and system. Moreover, to cope with innovation, we also need to change elements such as teaching materials and subject mater content, beliefs, attitudes and actions of the related people-especially teachers and the principal, and administrative support, and organizational culture (Fullan & Pomfret, 1997; Glatthorn, 1987, 2000). This study is part of a two-year project, which aims at investigating the critical factors related to instructional innovation-by studying the communicative approach to English teaching in junior high schools-and attempts to recommend feasible ways for teacher development to cope with school-based instructional innovation. This study employs questionnaire survey to investigate the problems or factors related to applying Communicative Approach to junior high school English teaching in Taiwan. The findings show that the success of instructional innovation is influenced by internal factors (concerning the teacher and learners) and external factors (other than the teacher and learners). The internal factors include learners' abilities, interest and motivation, and the teacher's belief, competence, and performance. The external factors involve the values of the society and parents, and the educational system. English teachers may not change the external factors, but try to improve and change the internal factors through teacher development, which can keep them up with the innovation to cope with the new challenges. Nevertheless, for the success of may instructional innovation, the reaching committee of each school, as a growth group, should take more responsibility for teacher development through activities such as cooperative learning and interactive discussions.