This communication leans on the results of a thesis concerning reports in the profession by the teachers. The starting point of our reflection is a comparison of the educational practices of the teachers of the primary, according to the schools of the town of Lille in which they work, but also according to their representations, their age in the profession and their manners to teach. This bringing together of the public teachers at a micro-local level makes us to think the impact of the theory which underlies our research and its effects. Indeed, our sociological entrance, which makes us insist on the trajectory of the teachers, does it favor an analysis to the detriment of the other one? But, while the science is established around the principles of the reproduction and the checking, how our results can present the scientific characters of the regularity and the stability? To analyze our results, we retain four imperatives allowing the development of an explanatory knowledge: 1/ our statements must retransmit a univocal speech, 2/ our results must bring a new "information", 3/ they must be refutable and 4/ they must be imbricated itself with other theories. Our communication will resume the data of our thesis in which we triangulons three dimensions: the professional representations, the daily practices and the trajectories of the teachers of elementary schools. Our methodology is quantitative, organized around two questionnaires. Our sample is constituted by 101 teachers, and by 177 trainees in second year of initial training (IUFM). Our sampling was established according to the characteristics of the elementary schools of the town of Lille: number of classes, number and socioeconomic categories of the pupils. In our research, by revealing the very strong influence of the teaching sociological trajectories on the educational practices, we find two types of reports. Methodological reports first of all: methodological reports first of all: the weak impact of the establishment for the benefit of the sociological trajectory also is to be reported in the micro-localization of our comparison. Epistemological reports then: the impact of the teaching sociological trajectories must be analyzed by taking into account the report between peculiarity and majority. The "particular", or singular, is usually defined as what is distinguishable. Conversely, the "general", or global, is what regular, even merged. Nevertheless, against an essentialist conceptualization of these concepts, the singular and the general cannot escape the critical examination of the structures which organize them. In other words, the private individual and the general are defined by their theoretical and methodological statutes: neither of them is of strictly empirical order. To conclude, our thesis project is well to build a reflection respecting the complex, multivariate, and multi-level nature of the relationship between the variables. The report "peculiarity of the practitioners / generalization of the practices" must be seen as a theoretical construction. So while conceiving this report we shall register our results in a critical prospect. Berthelot, J-M. (1990) L'intelligence du social. Paris: P.U.F. Boudon, R. (1971) La crise de la sociologie. Paris: Droz. Boudon, R. & Clavelin M. (1994) Le relativisme est-il résistible?. Paris: P.U.F. Bourdieu, P. & Passeron J.-C. & Chamboredon J.-C. (1968) Le métier de sociologue. Paris: Mouton/Bordas. Merton, R.K. (1997) Eléments de théorie et de méthode sociologique. Paris: Armand Colin. Passeron, J-C. (1991) Le raisonnement sociologique. Paris: Nathan. Popper, K. (1973) La logique de la découverte scientifique. Paris: Payot. de Singly, F. (1992) L'enquête et ses méthodes. Le questionnaire. Paris: Nathan. van der Maren, J-M. (1996) Méthodes de recherche pour l'éducation. Bruxelles: De Boeck Université. Weber, M. (1992) Essai sur la théorie de la science. Paris: Plon.