This study investigated Taiwanese English teacher misbehaviors in relation to college student motivation in English classes. The sample consisted of 344 college students from two types of universities -comprehensive universities and technical universities— located in central Taiwan. The participants were asked to respond to instruments designed to measure the frequency of English teachers5 misbehaviors (in a Taiwanese context) and their influence on students5 motivation for learning English. The results of the Pearson correlation indicated that English teachers5 misbehaviors were correlated negatively and significantly with students * motivation for learning English. In addition, multiple regression analyses revealed that five teacher misbehaviors were significant predictors of students，motivation for learning English. Findings of this study suggest that students * motivation for learning English is reduced when the English teacher exhibits the following misbehaviors: Unprepared and disorganized teaching, boring lectures, ignoring students5 need, unclear explanations, and failure to notify of changes. Finally, implications of these findings are discussed.