This study investigated the nature and validity of teacher judgments about student motivation as part of a project related to the teaching of mathematics. The study examined: (1) the degree of correlation between teachers' and students' assessments of students' motivation regarding mathematical topics; (2) the stability of teachers' and students' ratings of students' motivation across time; and (3) the coherence of ratings across different beliefs, goals, behaviors, and feelings. Teachers of grades 4-6 (N=28) rated 6 "target" students in each of their classes at the beginning of the school year, again after completing a fractions unit and a measurement unit, and at the end of the school year. The teachers measured each target student's mastery orientation, performance orientation, help-seeking, positive emotion, negative emotion, and self-perceptions of ability. All students completed a questionnaire on their own beliefs, values, goals, and feelings associated with math, within the same time frame. Students' ratings of their own motivation over time and across mathematical contexts were somewhat stable. Teachers judged students' motivation as more stable over time and context, and more coherent than students judged themselves. Results suggested that teachers may need assistance in making more differentiated and reliable assessments of beliefs, goals, and behaviors in students that are associated with motivation and learning. (Rating tables are attached.) (CK)