The law “for equal rights and opportunity, the participation and the citizenship of disabled persons”, dated February the eleventh, imposes to register all the students in their school district and to make it easy for disabled people to be schooled within the mainstream education system, as often as possible. School-life assistant or auxiliaire de vie scolaire (AVS) appear to aid and to guide disabled students. There are two types of AVS: the AVS individual (AVSi) who guides only one disabled student schooled in an ordinary class and and the AVS collectif (AVS co) who acts in special classes with disabled students. In this article, we throw light on the way the AVSi and the AVS co speak of the aid and guidance they provide in their practice in situ. We show how is organised and evolves each dissymetrical system (système bicéphale dyssimétrique, [Rev Fr Pedagog 151 (2005) 91–109]) made up of a teacher and a AVS, to help a disabled student. We collected the data in a special class (Classe d’intégration scolaire or Clis) for students suffering from a mental handicap and in an ordinary mid-class in French preschool education. We filmed two dyads composed of a teacher and an AVS in their ordinary practice and we interviewed these four actors. We observe the existence of differing systems between these two classes. The particular form of collaboration between teacher and AVS, shows that in fact, the actors’ respective places of and the way they share out the task depend on the system in which they work.