Background/Context: Despite the importance of students' active engagement for learning, little is known about how teachers create environments that are supportive of students' positive motivational and learning-related beliefs, particularly at the high school level. Furthermore, most of the studies that have described teacher practices in relation to students' perceptions of their classroom context have focused on elementary and middle school populations; much less is known about creating supportive contexts for high school students. We conceptualized supportive instructional contexts as multidimensional, developing a profile of student perceptions that would define a classroom that would promote and sustain students' motivation and learning, based on the literature on classroom motivation. This profile included perceptions of the motivational climate, the social climate, and the academic climate of the classroom. Purpose and Research Questions: The goal of this study was to identify high school teachers who were perceived by their students as creating classroom contexts that were particularly supportive of students' motivation and learning, and to describe their practice. The analysis was guided by these questions: How do effective high school teachers create classroom contexts that students perceive as supportive of their motivation and engagement? What underlying commonalities describe these teachers' instructional practices? A secondary question focused on whether there were any discernible differences between the contexts of high school science and social studies classes, or associated with teachers' gender. Participants: Students (N = 2,864) in Grades 9-12 from three high schools and 4 of their teachers (2 science and 2 social studies), identified based on students' survey reports. Research Design: Teachers were identified for observation based on students' reported perceptions of the instructional contexts of their classes. Observation field notes were analyzed thematically to develop a grounded model of teachers' instructional practices. Conclusions/Recommendations: Analysis of the field notes suggested a model that consists of three core themes: supporting understanding, building and maintaining rapport, and managing the classroom. Within this framework, a number of the teacher practices described served more than one of these three functions, and some, such as teacher movement and the use of varied participation structures, served all three. All the observed characteristics of practice were consistent across subject area domains, and differences in relation to teachers' gender were evident only in terms of teachers' use of humor in the classroom.