This paper aims to investigate the challenge-based learning (CBL) approach from the perspective of challenges and challenge providers (CPs), that is, how to successfully collaborate with external CPs and design challenges that work well in university courses and events. We base this paper on three pillars: literature studies, our own experience teaching CBL in two courses, one at Linköping University and the other at Twente University and interviews with companies and organizations that have participated in the courses as challenge providers. Regarding the literature studies, we can conclude that the literature on CBL, in general, is extensive. However, it is rather scarce when it comes to studies on how to work with challenges and especially with external CPs in practice; hence, there have not been many theoretical contributions from which to draw. However, those found are in line with our own experience. Through the analysis, we have created a list of learnings that hopefully can benefit organizers of CBL courses and events in their work of creating great challenges.