Over the last 2 decades, Irish schooling and society have gone through a period of significant structural and policy-driven change. To meet the emerging needs of the knowledge/learning society, schools and teachers are challenged to develop their capacities as "active learning communities". This places greater demands on teachers and schools to reflect on their classroom practices, to utilise a wider repertoire of pedagogic styles more suited to the needs of the 21st century learners and to meaningfully collaborate with their fellow professionals. Teaching and Learning for the 21st Century (TL21) was a 4-year (2003-2007) multi-pronged research and development project involving the Education Department at the National University of Ireland, Maynooth (NUIM) and 15 post-primary schools. The project sought to address a number of key aims in terms of developing schools as professional learning communities, including addressing the isolation and insulation which teachers can, and do experience in their day-to-day professional lives and prioritize quality in teaching and learning as a key challenge for school development planning. This paper attempts to succinctly frame the key developments and findings which emerged over the duration of this process. (Contains 1 table and 3 footnotes.)