Nowadays, being able to communicate ideas and thoughts in a second language is a paramount ability to actively participate in this globalized world. In that sense, writing has become an essential tool for expressing points of view and beliefs; hence, the development of this skill through formal education should be guaranteed for students since primary school. Moreover, the educators’ language teaching conceptions that can directly affect the instruction of this ability have not been deeply studied in the Licenciatura program, and considering they are the ones in charge of guiding the learning process, it is a defect in our educational system. Therefore, this qualitative project, which is framed in a Case study, is aimed to determine the transformations in the language teaching conceptions of a pre-service teacher during the design of a Didactic Sequence for enhancing writing abilities in English. This project comprises theoretical support provided by Rodrigo, Rodríguez, and Marrero (1993), Camps (2003, 2008), Pérez and Rincón (2009), Bonilla and Rodríguez (1997) and Muñoz and Servan (2001). This research is going to be carried out by one pre-service teacher who is a student of the Bilingualism Program of Universidad Tecnológica de Pereira. Since the researcher plays the role of complete observers, it is necessary to collect all the information through reliable data collection methods such as reflective journals, interviews, and a checklist. The first one allowed them to write down their conceptions and then analyze them. The semi-structured interviews and the checklist will provide feedback and control in relation to the experts' insights about pedagogical issues and the elements the didactic unit proposed.