Many factors influence the effectiveness of a school, including:its social context; school management and staffing; school organisation and class allocation or "streaming"; disciplinary climate; academic emphasis; and pupil-teacher interaction and involvement. This research study examines the question of whether there are significant differences between second-level schools in Ireland, in terms of exam performance, attendance and personal development, amongst other issues. The book focuses on the strength of the "school effect" in influencing pupil outcomes, and concludes with a number of policy recommendations.