This article reports on findings of a study which objective is the development of an instrument for systematic evaluation and improvement of the quality of teaching in special schools. The article describes the research process which led to the construction of the instrument as well as the way teachers can use the instrument to improve the quality of their teaching. The article advocates a practice perspective to professional development in special schools, as special schools in Denmark are under pressure by three international educational agendas: the agenda of accountability, the agenda of standards and the agenda of inclusion. The instrument suggests that professional development is teacher driven and not driven by the accountability agenda. The research approach was collaborative as 35 teachers and principals from 16 special schools participated in the research process. Their perceptions of quality in the practice of teaching in special schools and research literature on the quality of teaching in both mainstream schools and special schools have shaped the development of the instrument. Thus, the instrument is based on the finding, that teaching methods in general and special education are not as different as assumed. This finding is reflected in the instrument.