This paper is concerned with the ongoing influence of in-service teacher education upon teachers’ instructional behavior and attitudes. Thus the purpose of this study is to trace attitudinal and instructional changes after in-service teacher training and thereby identify either favorable or unfavorable factors affecting such changes in classroom settings. First, a survey was conducted to see which teacher training programs teachers preferred, uncover any changes in instructional behavior and attitudes as well as factors related to said changes, and gather suggestions for prospective teacher training programs. For additional data, four teachers’ reflective journals and interviews were analyzed. The results of the study were as follows: 1) teachers believed that a teacher’s techniques rather than their English proficiency have the most direct influence upon effective English instruction; 2) changes in both behavior and attitudes are observed for only a short period right after in-service teacher education; and 3) a major factor impeding change is the discrepancy between the English language curriculum and actual classroom instruction, which is largely due to the washback effect of the requirements of the Scholastic Aptitude Test required for college admission.