This thesis explores the policy of junior secondary education expansion in Tanzania between 2004 and 2012, implemented through a large-scale process of community mobilisation. It uses a political economy approach that defines education systems as social constructs, products of history, with material and ideological dimensions, embroiled in the politics and economy of a country and forged at the intersection of internal and external factors. The primary analytical vantage point is the elite. Four main dimensions of the policy are studied. First, the thesis sheds light on the politics of educational policy-making. The expansion policy is the outcome of intra-ruling class conflicts tied to competing modernisation philosophies. Yet, elites' educational choices are also underpinned by a widely shared symbolic system, rooted in the ideological history of the country but entwined with contemporary global discourses. Second, the thesis investigates the budget for secondary education, pitting the stated desire of elites for quality secondary education for all against their actual financial effort. Donors' interventions are also scrutinised to understand how they have contributed to shaping the policy and its narrow fiscal space. The thesis then examines local renegotiation of the policy at district level and unveils power struggles unleashed by its implementation in the local arena. Finally, this work studies the relationship between education and the economic sphere through an investigation of the textbook sector and documents the formation, at district level, of a politico-business complex around educational resources. The secondary education expansion occurred against a background of job scarcity, quasi-universal primary education and quality private education available to the wealthy. In this context, the thesis argues that under-resourced and under-performing community secondary schools may be interpreted as a renewed educational settlement to attempt to resolve the structural tension inherent in education systems between the integration of the youth and social differentiation.