To be able to collaborate effectively and efficiently has been described as a complex and crucial twenty-first century skill. During collaboration, however, a variety of problems may emerge that require groups to engage in effective regulation processes, which is a complex task in itself. Up to now, little is known about (a) what types of strategies learners of such groups typically apply to regulate their learning, and (b) on which social levels (self vs. co vs. shared-level) they apply these strategies to account for different kinds of problems that may surface during collaboration. To address these questions, we developed four case vignettes that described a study group during exam preparation, in which problems were systematically varied in a 2 × 2 within-subjects design (present vs. absent motivational or comprehension-related problems). Using an open-ended format, N = 278 students were asked to describe (a) the strategies they would apply, and (b) the social levels at which they would apply these strategies in each of the four problem situations. Answers were coded and quantified by aid of an in-depth, theory-based coding scheme. Results showed that students react to motivational problems with more motivational but less cognitive strategies and to comprehension-related problems with more cognitive, but a similarly high use of motivational strategies. Thus, students seem to tackle motivational problems in a more problem-sensitive way than comprehension-related problems -- a finding which was found also across social levels. These findings bear important implications for process-related research on social regulation and for the design of interventions.