This study explored middle school teachers' perspectives on and expectations of adolescence and puberty, using observations and interviews of 15 teachers in two Japanese middle schools and two United States (U.S.) middle schools, as well as a survey of teachers in selected schools in both nations. Teachers in the U.S. described puberty as being longer for males than for females. Among Japanese teachers a tighter fit was observed between periods of puberty and rebellion, while U.S. teachers saw adolescent rebellion as ending well after the end of puberty. Analysis of language and discourse suggested that Japanese words for middle school students imply compliance, energy, and active engagement in study and clubs; Japanese informants predominantly viewed middle school students as still being children, and were never expected to engage in dating. The social construct of hormones as an intoxicating and distracting force was common among U.S. teachers, while Japanese teachers did not link puberty with hormones or disruptive behavior with sexual energy. Implications of these cultural differences for the effects teacher expectations have on student performance and behavior are discussed. (Contains 24 references.) (PB)