Abstract : This thesis analyzes the influences of social interactions on the economic behaviours of households. The estimates on data of Ivory Coast make it possible to show two types of results. Firstly, the probability of working on a segment of job market grows with the proportion of the individuals of the group who work on this segment. Secondly, the temporal reversibility of consumption is rejected for some expenditures such as Food and Transport : the spending patterns play an important role. Moreover, the Housing expenditure and Transfer is most sensitive to social environment and thus most subject to ostentatious uses. In addition, an theorical model explain the linkage between conspicuous consumption and the need for social recognition in the group.