Notwithstanding the relevance of maturity assessments in practice, Information Systems (IS) research has – despite exceptions – yet rarely endeavoured into reflecting and developing theoretically sound maturity models. This paper reports a literature review on maturity models in the IS domain. Specifically, it explores what type of research on maturity models has been undertaken (retrospection) and which potentially useful measures might be pursued in IS for future research (prospection). The paper suggests that research on maturity models is of growing interest; nevertheless, comparably few related articles have been published in the leading IS journals. We see that the Capability Maturity Model (CMM) and its successor CMM Integration (CMMI) dominate studies of maturity. While maturity models have been addressed in prescriptive, descriptive and reflective works, the notions of maturity and maturity models have rarely been conceptualised in detail. In view of that, the paper presents implications for the practice of maturity model application and research thereof.