The aim of the research is to reveal the relevance and the identity of the modern Spanish school buildings through three unknown and unprotected cases. Three schools which are holders of the values of modern architecture. However, their survival has followed different paths in order to their permanence and transformation. These are projects whose validity remains but in which the pass of the time, and their owners management, have interceded in their actual state. So that we can find different approaches and strategies of transformation in each of them: Preservation and enlargement: “Betània-Patmos School” (Barcelona, 1963-69), Arch. Giráldez, López-Íñigo and Subías. Conversion and enlargement: “Bell-Lloc School Residence” (La Roca, Barcelona, 1964-68), Arch. Baldrich. Preservation and replacement: “Aula European School” (Barcelona, 1968-71), Arch. Cosp. The methodology focuses on the analysis of the original projects, its construction, but also through their particular evolution until nowadays. The final objective is to identify and evaluate potential intervention criteria, applicable to other cases, in order to avoid cases such as demolition.