Manufacturing firms increasingly search for new ways of differentiating themselves from competitors by offering innovative customer solutions which can be defined as customer-specific bundles of products and services. This endeavor is a transformation process that has to be managed by manufacturers who often lack two things: insights into where they actually in the process, and useful advice on how to advance. Our objective is to develop a comprehensive maturity model that can assist this transformation. We identified six academic approaches that deal with this transition from different viewpoints in order to derive a consolidated concept of maturity in this domain. We show that these maturity models already give a good impression of what maturity in providing customer solutions is. Nevertheless, we identified shortcomings that we will address in our further research process.