This work is the result of a doctoral thesis that studies the extension of the school day, part of a qualitative research approach, presenting a case study as a research strategy, which aimed to analyse the experiences of extending the school day through the Mais Educação (More Education) programmes in Brazil from 2010 to 2013 and the Escola a Tempo Inteiro (Full-Time School) programme in Portugal. In the first stage of the research, bibliographic sources related to the topic in question were sought in order to define the theoretical framework for analysis, based on national and international authors. From there, a literature review was prepared to complement the analysis of the topic in question. In the second stage, the schools participating in the research in Brazil were selected. The third stage consisted of data collection in Portugal, while the fourth stage involved field research in the selected schools, based on the IDEB (Basic Education Development Index). The fifth stage consisted of a roundtable discussion with the participation of the Mais Educação Programme monitors, and the final stage was a roundtable discussion with the directors and coordinators of the Mais Educação Programme.