The present thesis on bilingual education, with its foci on linguistic heterogeneity and language policy 'from below', covers the first 15 years in the officially multilingual new South Africa. The post-apartheid era has seen South Africa's pro-multilingual Constitution and the language-in-education policy for schools being sidelined in favour of an English-oriented mindset. The subversion of the policy's additive bi/multilingual intent in favour of a replacive 'English-as-target-language' approach indexes a collusion between the political class and the African-language speaking majority, and has been accompanied by systemic underachievement. While the linguistic market beyond school is not necessarily unified in its monolingual habitus, choices for the poor are constrained by a lack of alternatives. Within the implementational spaces afforded by the policy environment, groups such as Project for the Study of Alternative Education in South Africa (PRAESA) have attempted to demonstrate an alternative approach that valorised mother-tongue-based bilingual education. These alternative education initiatives (1995-2009) form the substance of the five published pieces in the present portfolio, capped by the summative thesis. They were written while the author was still a member of PRAESA, and collectively address topics such as language policy initiatives 'from below', the role of surveys in gauging language behaviour and creating language awareness, a multilingual training of trainers programme for southern Africa, a bilingual teacher in-service programme foregrounding different teacher identities in relation to policy realisation, and a classification system for schools by language medium that factors in mother tongues while making allowance for linguistic heterogeneity. The thesis reflects critically on the prevailing monoglossic language ideology informing these studies, and suggests the need for a heteroglossic approach oriented to language as a resource.