The focus of my thesis is on the development of a multi-method framework for the validation of formal models (domain model, user model, and teaching model) for adaptive work-integrated learning. In order to test its general applicability, the framework will be applied in four different realistic work domains. In this article, specific challenges of traditional validating approaches in work-integrated learning are being discussed. Eventually, the core ideas and methods of the validation framework are outlined. Formal Models for Adaptive Work-Integrated Learning Formal models are used for realizing adaptivity in adaptive learning systems. These formal models together fulfill the functions of a domain model, a user model, and a teaching model [1]. The domain model contains the structured expert knowledge in the learning domain, i.e. those domain concepts which are relevant for learning. In many cases, the domain model also specifies relations among domain concepts. For example, statics, s...