In this paper we introduce a measure for inclusion of two IFSs into each other according to the two main partial orderings in the family of IFSs. This inclusion measure will be observed on few levels. From a set-theoretical point of view, intuitionistic fuzzy point of view and ordinary fuzzy point of view. We also employ the notion of the two modal quasi-orderings, the necessity and possibility, known for intuitionistic fuzzy sets. All of these inclusion measures can be applied in real world models where intuitionistic fuzzy sets are employed.