This paper proposes the use of activity theory and multi-level activity systems as a framework to analyse the effectiveness of ICT integration in Singapore secondary school classrooms. Three levels of activity systems are developed to study the effectiveness of ICT integration at the classroom: the classroom activity system, the department activity system and the school activity system. A multiple case study approach with three secondary schools in Singapore was adopted to provide in depth understanding of the socio-cultural factors that affect ICT integration in the classrooms. The findings show that schools need to function as learning organisations to be adaptable to changes, especially rapid changes brought about by technology integration in curriculum. To be successful learning organisations, schools need a curriculum focused, over-arching ICT goal to provide clear direction to the key players--teachers, HOD/ICT and instructional program HODs in the school. The management approach to ICT integration in the school should be through distributed leadership. While the school principal sets the tone for the school vis-a-vis modelling curriculum focused integration, providing encouragement to teachers and support for the HODs plans, the role of the HOD/ICT should be to ensure the relevant ICT-enabled infrastructure and implementation procedures are in place. (Contains 1 table and 12 figures.)