In this paper, we propose a study of progressive development of the structure of corpus collected starting from the discussion forums. These are the first results from an ethnographic description of constitution and analysis practices of a corpus located within an interdisciplinary project. At first, we describe the personal digital documents folder of a researcher, relative to his corpus analysis of interactions of social support online. Next, we examine the constitution of a shared corpus, result of the pooling of individual corpora, small size, produced by researchers participating in the project, each individual corpus reflecting his producer's perspectives of research.