The question of the informal economy is undoubtedly one of the most worrying and high-stakes issues that is posed with force and acuity in underdeveloped societies, where this phenomenon is very much present and never ceases to be the subject of numerous debates on development issues.The scale of these so-called informal economy activities makes them a concept that should no longer be considered as such. The phenomenon of the informal economy has proved its worth in a Congolese society that is over sixty years old, where it is also the largest provider of jobs and income.The present study, which is part of a social economy approach, highlights the relevance of reconsidering the impact of the Congolese informal sector. Based on an empirical approach undertaken in the megalopolis of Lubumbashi in the south-east of the country, this study evokes the importance that these micro-enterprises (commercial or managerial micro-enterprises and subsistence micro-enterprises) must and should have in any coherent national development policy.