Teachers' skill in inferring students' reading motivation influences their ability to provide responsive literacy instruction. Yet, studies show that convergence between students' and teachers' reports of students' affective experience with reading is moderate to poor. The present study, with a sample of 140 students, and 15 middle school teachers, examined the convergence across different rater reports (teachers, students, and research observers) of reading motivation and behavioral engagement in daily reading activities as well as the factors that explain teachers' perceptions of students' daily behavioral engagement with reading. Results indicate that there was no correlation between teacher or research observer reports with student ratings. However, teachers' perceptions of students' behavioral engagement in reading was explained by stable as well as situated student indicators of reading engagement. Additional measures to help teachers more easily detect shifts in motivation as a function of classroom practices are discussed.