The ComMod (Companion Modelling) and Gerdal (Group for Experimentation and Research: Development and Local Action) approaches facilitate the emergence of solutions and action plans negotiated within peer groups or arenas of heterogenous actors by stimulating interactions between their participants. Their theoretical, ethical and methodological foundations are described, and two case studies illustrate their use. In order to help practitioners reflect on their mode of intervention to collectives, the comparative analysis of these approaches highlights the key points of their accompaniment, such as the initial situation, creation of relevant collectives, management of processes, sharing of knowledge and points of view, monitoring and evaluation of effects, and strengthening of the capacity of collective innovation.