This thesis examines the state of reporting Lessons Learned in a Swedish company that operates globally and explores the areas of potential improvements through better classification and reporting of Lessons Learned from previous projects. Particularly, it explores which the most effective ways to capture and document Lessons Learned are as well as how a System that supports efficient storage, sharing and retrieval of Lessons Learned can be specified. The research is a case study in a Swedish company and is a mixed-model research as it uses both quantitative and qualitative data from primary sources. Indeed, the data collection was done via interviews, questionnaires, a focus group and the study of the company’s documents. The findings revealed some issues in the Lessons Learned methods used in the company, especially in documentation. Additionally, the need for a Lessons Learned System to manage the knowledge and experience from projects was also identified. The thesis concludes with explicit answers to the research questions and more specific with the suggestion of certain guidelines for the employees, a new template for reporting Lessons Learned and the specifications of a Lessons Learned System that can support efficient storage, sharing and retrieval of Lessons Learned.