Digital maturity models are not widely adopted or implemented in business practice, despite the interest in these models. It is unclear which dimensions and parameters are most crucial in measuring the level of digitalization within small and medium-sized enterprises. In this paper, we present a systematic literature review of studies on digital maturity models published from 2011 to 2021. The guiding research question of this study is: Which dimensions are included in digital maturity models to measure the level of digitalization in business models of SMEs? Existing research on the dimensions and parameters included in digital maturity models was reviewed. The review identified nine dimensions: (a) strategy, (b) leadership, (c) culture, (d) organization, (e) people/employees, (f) technology, (g) processes, (h) products, and (i) customers. Additionally, 16 parameters were identified that measure these dimensions. This paper concludes with a discussion of the implications of this review for future research and practice.