This study investigated high school teachers' perceptions of the motivational needs of their students and the strategies they used to address those needs. Participants were 96 teachers in 15 high schools in a Southwestern state in the USA. Data were collected via paper-based questionnaires addressing teachers' perceptions of: supportive classroom environment, students' general motivation, causes of student lack of motivation, teachers' self-efficacy for motivating students, interpersonal style, and motivating strategies. Quantitative data were analyzed by correlation and multiple regressions. Teachers' efficacy for diagnosing and intervening for students' motivation, and their interpersonal motivating styles, predicted their strategy use. Both internal and external causal perceptions explained important parts of variance in teachers' perceptions of students' overall motivation. Strategies that teachers use, in turn, predicted the supportiveness of their classroom environments. Surprisingly, teachers' perceptions of causes of motivation did not predict either environment or strategy selection. Implications for educational policy and classroom practice are discussed. (Contains 1 note and 4 tables.)