Hendrik Drachsler defended his PhD thesis on developing recommender systems to help learners find personalized paths through informal learning networks. His research included a theoretical background study, a psychology experiment, and a simulation of learning networks. The goal was to address the problem of learners feeling overwhelmed by the large amount of information in learning networks by creating a recommender system prototype that could suggest personalized learning activities and paths based on a learner's interests and previous activities. The conclusion was that recommender systems designed specifically for learning networks can help lifelong learners more efficiently pursue personalized learning goals.