This paper provides an overview and guidance for the long term planning of education systems in the context of Education for All and the Millennium Development Goals. It argues that long term gains in educational access depend on anticipating future financial and non-financial constraints on growth and on successful implementation of plans which support growth that can be sustained. Examples are provided of recent expansion of primary schooling which failed to take a sufficiently long term approach to growth and has risked the creation of resource bottlenecks, poor trade offs between quality and quantity, and dependence on uncertain financing.