Research findings concur in demonstrating both that collective settings spur teacher development, and that changes in teacher approaches and practices depend on some conditions (Grangeat, 2012). These conditions specify a new way for teacher training. This kind of collaborative settings is frequently called 'Inquiry Based Continuing Professional Development program' since all the actors involved in this IB-CPD program endeavour to resolve the common problem but any of them know the solution of this problem. This paper addresses a specific IB-CPD program that involves teachers from two lower secondary and four primary schools within a urban sector in France. A first question is to describe and understand the basis and the structure that underpin this programme. A second question is to figure out a set of variables that will be monitored in order to regulate and evaluate the program efficiency.