The Threshold Project, a 3-year project that followed a 1985 pilot study, examined the nature of the language and learning difficulties that black Standard Three (Std 3, or grade 5) children in South Africa experience when they change from their mother tongue of Sepedi to English as a medium of instruction and learning, a policy known as "delayed immersion." This main report of the Threshold Project summarizes the five final reports of the project and constitutes an integration of the analysis in terms of three parameters: historical-political, socio-cultural, and educational-systemic. Specific educational aspects covered include the following: school-based teaching and learning experiences; English as a subject; the disparity between English as a subject and English as the medium of instruction; learning content subjects; local models of teaching and learning; curriculum development and reducing the disparity between junior and senior primary phases; possible English language policy models; moving from English as a subject towards using it as a medium of instruction; and principles and processes of materials development. Contains a list of 107 references. (LB)