We investigated the premise that observation measures of instruction are indicators of effective teaching, using the definition of effectiveness articulated by departments of education: teaching that boosts student achievement. We argued that student motivation is equally as important as achievement in the evaluation of teaching effectiveness (TE); therefore, we examined students' (N = 145) achievement and motivation outcomes. We scored 40 lessons (from 10 kindergarten teachers) with two TE observation measures: the content-independent Classroom Assessment Scoring System (CLASS) and the content-specific Reformed Teaching Observation Protocol (RTOP). We found that the two measures' scores were related differently to student outcomes. Instructionally supportive practices (CLASS and RTOP total) predicted achievement and motivation. Emotional support (CLASS) was positively related to motivation but not to achievement. Classroom organization (CLASS) was negatively related to both motivation and achievement. The CLASS total score did not predict student outcomes; its use masked differences across domains of teaching practices.