Most theories of self-regulated learning (Winne & Hadwin, 1998) assume that adaptability is one key competency of self-regulation that should be associated with success in learning. Within previous studies, learners indeed demonstrated significant adaptation to task complexity; however, empirical results so far do not indicate a straightforward positive relationship with learning success (Pieschl, Bromme, & Stahl, submitted). In this study, students (n = 129) solved three differently complex tasks within a hypertext. Their learning process was captured in detail and showed significant adaptation to task complexity on all variables. For example, students spent most time on the most complex task. Additionally, we analyzed two important but independent indicators of learning success: quantity and quality. In both cases, successful students strongly adapted their learning to task complexity. Additionally, quantitatively successful students followed a high-speed strategy whereas qualitatively successful students followed a deep-elaboration strategy, especially for the most complex task.