The political and social rationale for the establishment of a national system of education in nineteenth-century Ireland has been the focus of considerable attention by scholars. Less attention has, however, been paid to teacher quality and school effectiveness within that system. Various efforts were made over the course of the century to address the issues of teacher quality and school effectiveness. The paid monitor was introduced in the early 1840s to convent and ordinary national schools, with paid pupil--teacher programmes recognised in the larger convent and national schools during the same period. A more strategic effort was made to address the issue of teacher quality with the introduction of an in-service type intervention from the mid-1850s to provide a school-based programme for teachers and managers in effective school organisation. Examining this intervention is the purpose of this paper: what was its rationale and purpose, how was it planned and implemented; what was its impact and what is its historical legacy?