This study investigated Iranian high school teachers' conceptions of effective teaching and examined the relationship of those conceptions to their teaching practices. The authors tried to achieve the purpose through questionnaires, observation, and interview. These teachers identified "being student-focused" and "being exam-oriented" as the most important indicators of effectiveness. "Encouraging the students' involvement in learning," "being exam-oriented," and "using the novelty of methods" were identified as the most common teaching practices. A high consistency between the teachers' conception of effective teaching and their corresponding teaching practices was observed. Interview and observation confirmed the results of the survey. Implications for teacher professional development, teaching standards, and teacher improvement are discussed.