The AGATE project proposed the SEPIA system that allows an assistance designer to define assistance systems added in target applications. In Interactive Learning Environments, such assistance systems are useful to promote the acquisition of knowledge. These assistance systems consist of a set of aLDEAS rules. Our study of assistance in existing applications shows that the articulation between the rules of assistance can take many forms. We propose and implement a model of articulation between assistance rules with the five modes of articula-tion that we have identified. This model makes explicit and facilitates the definition of articulation between the rules of an assistance system.