Teacher quality is widely recognized as influencing student achievement and success in school. In this article, we consider various approaches to the assessment of teacher quality, including process-product observational measures, evaluation checklists, professional standards, large-scale surveys, and commercially available observation systems. We present examples of each from the special education literature, consider teacher education research genres for which each is appropriate, and evaluate each using a set of criteria that incorporates both practical and technical considerations. We advocate for multi-method approaches to teacher quality research and for more research relating what teachers know and do to what students learn, and we note that a stronger link between teachers and learners would allow for more rigorous evaluations of teacher preparation.