Recent years have witnessed a burgeoning interest in the study of teacher motivation. Although links between teacher motivation and teacher well-being, commitment to the profession, and other teacher-related outcomes are well-documented, prior research on associations between teacher motivation and student outcomes has been less consistent. This article focuses on teacher motivation as situated within two prominent frameworks: self-determination theory and achievement goal theory. First, two systematic reviews of research on self-determination theory and achievement goal theory are conducted to examine whether, when, how, and why teachers' motivation may influence--or at least relate to--which student outcomes. The processes by which teacher motivation is associated with student outcomes, such as via specific instructional strategies, are also taken into account. Second, the question of why research on teacher motivation often fails to find consistent effects on student outcomes is considered, including where in the complex chain of events from teacher motivation to student outcomes the signal gets lost. Third, the need to study the reverse ordering of effects, reciprocal effects, and the dynamic interplay between teacher motivation and student outcome variables is discussed.