There is a need for valid, cost-effective assessments of effective teacher practice that can be used as an alternative to observational assessments. This paper examines one alternative, coaches' reports, by comparing ratings of teachers' interactions with children using two measures: the Teacher Knowledge and Skills Scale (TKSS), a coach-rating measure, and the Classroom Assessment Scoring System (CLASS), an established observational measure. The study also examines the role that the coach-teacher relationship plays in coaches' ratings. A sample of 162 early childhood teachers and 12 coaches implementing a coaching intervention participated in this study. Results show that coaches provided ratings similar to those of trained observers, but they also tended to rate higher the interactions of teachers with whom they have higher-quality relationships. The paper discusses the implications of these findings for the assessment process in early childhood education. (author abstract)