This paper considers the constraints and contextual realities that may limits to Growth of Non-Government Private Schooling in Sub Saharan Africa. There is evidence that in some poor countries private provision has been growing especially at the secondary level. The reasons for this include excess demand, differentiated demand, and the opportunities created for entrepreneurs by newly liberalised regulatory frameworks for educational services. This paper draws attention to the diversity of non-government private provision. It also presents estimates of the numbers of children currently out of school and their location in Sub-Saharan Africa. The extent to which exclusion is related to wealth, location and gender, focusing on economic constraints is discussed. Costs related to teachers are modelled to indicate likely minimum operating costs for unsubsidised schooling. It offers an analysis of the underlying demographic realities of expanded enrolment to reinforce the need to understand the magnitude of the task of achieving the MDGs and the need to identify mechanisms that expand services to large numbers of school-age children drawn from the poorest households.