Computer Science (CS) is a relatively new disciple and how best to introduce it to new students remains an open question. Likewise, the identification of appropriate instructional strategies for the diverse topics that constitute the average curriculum remains open to debate. One approach considered by a number of practitioners in CS education involves Problem-Based Learning (PBL), a radical departure from the conventional lecturing format. PBL has been adopted in other domains with success, but whether these positive experiences will be replicated in CS remains to be seen. In this article, a systematic review of PBL initiatives in undergraduate and postgraduate CS is presented from a Computing Education Research (CER) perspective. This includes analyses of a range of practical didactic issues, including the degree to which PBL has been systematically evaluated, practical problem description in the literature, as well as a survey of topics for which a PBL approach has been adopted. (Contains 2 figures and 2 tables.)