Extended abstract: Our study aims to describe and characterize the process that students go through in the Thesis Proposal Writing Seminar of a Master´s Degree in Teacher Education. The master´s students are teachers with years of professional practice, although with no or little experience in research. The master´s degree requires them to engage in the research on professional educational practices through a final thesis with specific theoretical and methodological characteristics. They have to observe and analyze the professional activity (its challenges and incidental learning) of an educator (teacher, school principal, librarian, advisor, etc.) in a workplace situation. In the thesis proposal writing seminar, which lasts for a year and a half, participants are therefore confronted with new social practices, typical of communities that produce knowledge in education. They begin to explore these practices especially when they face the written elaboration of a thesis proposal in the writing seminar. The seminar accompanies the process through multiple ways, in particular through collective oral discussions of their successive drafts. Joining this new community of practice, with their typical ways of doing, reasoning, writing and valuing their tasks, entails a great deal of dedication from all participants, with attempts and reattempts, full of tensions. The seminar guides and supports them so that they begin to participate in these practices through the elaboration of their thesis proposals and the reflection on the tasks involved. Our research aims to characterize this process. To do so, we will start with the content analysis of the portfolios submitted by the master´s students at the end of the seminar. These portfolios include a selection of written drafts and accounts of situations experienced in the seminar that they consider particularly significant for the advancement of their thesis proposals, as well as a reflective justification of why they have selected them. Based on their points of view, we will study the situations they have chosen, for which we will examine the corresponding documentary and observational material: video recording of sessions, drafts of the proposals, written participation in the virtual platform, etc. The analysis will relate a) the selection of significant moments made by the students in their portfolios, together with their reflection on these moments, and b) the situations pertaining to the seminar to which they refer in the portfolios. The results of this study will contribute to understanding the processes of teacher professional development (the constructive activity) involved in the elaboration of a research proposal (the productive activity). This genre is typical of research domains and unfamiliar in the teaching profession. We aim to identify the challenges and tensions that students experience, and the facilitating resources that help them in their way. ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Paper presented at the International Researchers Consortium Workshop (2023 CCCC Workshop on International Research: Texts, Institutional Contexts, Framing Theories) as a pre-conference workshop at the College Composition and Communication Conference Annual Convention, Chicago, IL, 2023. ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Trabajo presentado en el taller del Consorcio Internacional de Investigadores (Taller sobre investigación internacional: "Textos, Contextos institucionales y Marcos teóricos"), como actividad pre-congreso, dentro del College Composition and Communication Conference Annual Convention, Chicago, IL, 2023.