Teachers' perceptions of self-efficacy are one of the few individual characteristics that predict teacher practice. There is limited research linking teachers' perceptions of self-efficacy and actual classroom practices. The study examined teacher' perceptions of self-efficacy and actual instructional and behavior management practices using the Classroom strategies assessment system (CSAS), a multidimensional validated observation system. Fifty-eight Greek teachers completed the Teacher sense of efficacy scale (TSES) and were observed using the CSAS by independent observers. Significant differences between teachers' self-reported self-efficacy and observers' ratings were found in the domain of instructional strategies. Implications for research, professional development and school psychological practice are discussed.