This article presents the structure of the Corpus International Ecologique de la Langue Française, an extensive corpus of spoken French that will soon be available on the Internet, from both an epistemological and empirical perspective. Explanations are given with regard to the ideas that guided the data collection (ecological approach, comparability of the different areas of the Francophonie and communication situations) and to the choices made ("communicative spaces" and "activity types") with a view to relevant analyses in various research fields (variation, interaction, multimodality, French in contact, oral syntax) and an attempt is made to fill existing gaps in the current corpus. The article further addresses the issue of building up a network of experts, problems that had to be solved during fieldwork in the different areas and questions concerning standardisation, archiving and publication of the collected data (audio and video recordings, transcriptions, metadata), whereupon several examples are presented for comparative analyses.