Purpose - The purpose of this thesis is to investigate how two Swedish companies conduct their lean work, what similarities and differences they have in their lean-maturity and also how a higher level of lean-maturity can be generated.  To fulfil the purpose the following three questions where formulated:   How do the two companies conduct their lean work? What level of maturity do the companies have in their lean-work and what similarities and differences occur between them? What should the companies focus on to reach a higher level of lean maturity?   Method - To fulfil the purpose of this thesis a literature review and case study was conducted in two companies. The companies are referred to as company X, and Y in the report. The case study was conducted through a survey, interviews and observations. The data were compared with a theoretical framework and generated into the study´s results.   Findings - Both companies conducted their lean-work in a successful way, which means that they have a higher lean-maturity level than the average in Sweden. Generally it is about building a solid foundation and then gets the employees to follow the system that was built up. The result of the thesis showed that both companies have a higher level of maturity then the Swedish incision within all the 14 principles but despite this both companies have a lot to improve.  In the thesis multiple improvement suggestions have been made for the companies and the first thing they need to focus on are to build a solid foundation in the lean philosophy. The companies need to create a common target and get a functional system to be able to higher their maturity level. Another important factor is to focus on lean- and leadership-education, which will result in a higher level of knowledge.   Implications - The thesis have resulted in a few areas for improvements for both companies.  Other companies with the same conditions as case X and Y can probably identify their level of maturity and also follow the suggested improvements that are presented. In the thesis no new theories have been used instead existing theories have been used but in a different context.   Limitations - The thesis contains a two case study since the study is conducted in two companies. The thesis could easily been conducted in even more companies to get the result more trustworthy and also get higher generalizability. The survey that was used in the thesis had a few flaws since it is general and takes a production perspective. Since companies usually never work with lean in the same way the flaws may have affected the result of the thesis. Keywords - Lean, Maturity, Assessment, Lean 14 principles