The popular event Nuits des étoiles has become in France the summer encounter with the sky. More than 400 events are set up for three consecutive days each year: several thousands of voluntary organisers invite more and more people to observe the heavens and discover astronomy. Each summer, those collective star parties reach about one hundred thousand people, several millions of sky maps are printed and distributed by newspapers and the associated TV live program broadcast by France 2 channel interested 1 to 3 millions spectators. Since 1991, Nuits des étoiles has helped to develop organisations at the local level and increased the stakeholders' interest in general public awareness. It contributed in France to strengthen and professionalise an astronomical leisure offer.