The problem this work aims to solve is the improvement of the leanness level of a company jeopardized by the lack of lean philosophy engagement. The objectives of the research are to present a method based on a lean self-assessment approach, consisting of a qualitative self-assessment method based on lean elements that drive an index definition associated with the directives for lean to be implemented in a company (leanness roadmap). The method consists in providing the directives for lean to be implemented in a company (leanness roadmap) for the assessed enterprise composed by the company's lean index, recommendations, and countermeasures deriving from Delphi and Kendall Coefficient of Concordance (W) application among lean experts, leading the assessed enterprise to achieve results in terms of lean philosophy engagement, autonomy, and decision support criteria for future resource allocation. The results demonstrated that the method can highlight gaps where additional improvements and investments would be necessary for the assessed enterprise. Finally, the study concludes that the lean performance identification associated with the directives for lean to be implemented in a company (leanness roadmap) in a company can be a highly effective tool to improve lean adoption in a leanness enterprise.