A study examined teachers' perceptions and students' literacy motivations to assist teachers in bolstering students' self-determination and literacy competence. The theoretical framework was derived from E. L. Deci's self-determination theory which focuses on individuals' opportunities to make choices or decisions about how to behave or think as precursors to perceived control. Subjects were teachers and students in grades 3 to 6 who participated in a quantitative phase (n=68 teachers ; 374 students) and a qualitative phase (n=6 teachers; 6 students). A questionnaire was developed that represented 6 motivational domains: activity, autonomy, social, topic, individual, and writing. Student motivation was gauged by asking teachers to rate the frequency of each child's engagement in reading-related activities. Each teacher completed questionnaires on a half-dozen students. In the qualitative phase, students were videotaped during regular classroom reading lessons for 30 minutes. Teachers were interviewed after viewing a videotape of their students. Teachers' perceptions of students' literacy motivations on the questionnaire and on the personal interviews were generally consistent, with patterns of differentiation between motivation categories revealed more prominently on the teacher interviews. In general, findings confirm that teachers appear to possess an implicit theory of the association of self-determination and achievement that is highly compatible with Deci's perspective. Higher achievers were intrinsically motivated and self-determining. Less well-accomplished students were more dependent on external environmental supports for literacy. (Contains 50 references, 5 tables, and 1 figure of data. The Teacher Perceptions Questionnaire, teacher interview questions, and scoring examples are attached.) (Author/RS)