The aim of this thesis is to understand the World as a full-fledged object, namely as the space of a society. This objective is at the same time necessary and problematic. It is necessary because the sudden end of the Cold War entailed the need of new conceptual frameworks to understand the World without the confrontation of two ideological blocs. In parallel, the acceleration of globalization based on transnational and reticular processes profoundly questioned the apportionment of the World in territories and the classical distinction between the national and international spheres. This phenomenon also brought about the emergence of social issues (such as AIDS and climate change) and of non-state actors (such as globalized companies and Non-Governmental Organizations) which cannot be understood without taking into account their global dimension. Faced with these profound changes, it is important to be able to apprehend the World in its global dimension, going beyond its economic aspects. The so-called Global society model, which considers the existence of a global society as a possible option, allows this. However, the methodological nationalism – on which social sciences were based and according to which each society is necessarily linked with a territory, a State and a nation – makes it difficult to use this model to understand the World. Social sciences concepts, theories and methods were developed to conceive the World as a sum of objects (i.e. states, civilizations) and not as a full-fledged object. To go beyond this limit, the approach of this thesis is to apprehend the World through its issues and actors. In particular, I tried to understand if, and how, the involvement of the Lafarge company in the fight against the HIV/AIDS epidemic between 2002 and 2005 contributed to the development of a global society. Through the results of participant observation and an analysis of non-directive interviews with managers from Lafarge who were involved in the development of the company's AIDS program, I identified three main contributions to the emergence of a global society. First, the company contributed to the social construction of the AIDS epidemic as a global issue : in particular, the global approach the company adopted to deal with the AIDS epidemic was notably different from its traditional modus operandi in the field of social responsibility based on a local and decentralized approach. In addition, through its decision to provide its employees, their families and sometimes local communities with antiretroviral treatments in certain circumstances, the company participated in global controversies on cost-effectiveness of triple therapy, use of generic drugs and health as a global public good. Second, Lafarge's AIDS program contributed to reinforce the global dimension of the group, mainly by providing the power of the corporate with legitimacy, but also by contributing to the development of a global identity and by promoting interactions among subsidiaries. Third, the company contributed to building a global political arena, in particular through its interactions with a series of other global actors belonging to the same responsibility community. These interactions created legitimacy, transparency, institutions and norms at the global level, contributing to the emergence of a transnational deliberative arena. This thesis thus shows that it is possible to view the world as a full-fledged object and to overcome methodological nationalism by studying transnational objects, such as a globalized company and a global issue. It shows that Lafarge's involvement in the fight against AIDS contributes to the emergence of a global societal reference with a strong political dimension.