This study was an investigation of Japanese high school teachers' (N=139) beliefs and practices regarding communicative language teaching (CLT). Four research questions were posited concerning the beliefs that Japanese high school teachers hold regarding CLT, how Japanese high school teachers use CLT in the classroom, how Japanese teachers' beliefs and practices differ between academic and vocational high schools, and how the beliefs of Japanese high school teachers, their classroom practices, their learning experience, pre- and in-service training, perceived teaching efficacy, and contextual factors relate to and influence each other regarding the use of CLT. In order to provide answers to these questions, a survey, classroom observations, and interviews were conducted. Before conducting the quantitative analyses, the questionnaire data were analyzed using the Rasch rating-scale model to confirm the validity and reliability of the questionnaire and to transform the raw scores into equal interval measures. Regarding the first and second research questions, the descriptive statistics showed that despite holding positive beliefs about CLT, the respondents to the survey did not frequently use communicative activities. With respect to the third research question, a MANOVA indicated that the types of schools (academic and vocational) did not significantly influence the survey respondents' beliefs and practices regarding CLT. Concerning the fourth research question, the Pearson correlation coefficients showed relatively strong correlations between (a) Classroom Practices and Student-related Communicative Conditions (r = .56) and (b) L2 Self-confidence and CLT Self-efficacy (r = .55). Also, the best fitting path model indicated that (a) Student-related Communicative Conditions impacted Classroom Practices, (b) Positive CLT Beliefs indirectly influenced Classroom Practices via CLT Self-efficacy, and (c) Exam-related Expectations affected most of the indicator variables and Classroom Practices. Related to this, qualitative results indicated that the respondents' learning experience, in-service training, and contextual factors influenced their beliefs and practices. / CITE/Language Arts