Despite their high participation rate in, and strong attraction to, culture and sports centres, 15- to 30-year-olds are still insufficiently present in the associative sphere compared to their proportion of the French population. This article presents an analysis of variations in degrees of commitment, from those who simply participate in activities, to those who assume responsibilities in associations, on the territory of a French département. We have adopted several levels of observation in our local analyses, and therefore relied on materials ranging from general statistics to more detailed and first-hand data. Our results allow us to draw up a typology of the associations surveyed, with fatalistic, protective, and educational types. They also highlight the existence of associative “oases” and “deserts” – consequences as well as causes, among others, of strong disparities among 15 to 30-year-olds. In this context, the places they live in have as much of a social impact as social conditions.