Product lifecycle management (PLM) is a strategic and holistic approach for the management of information, processes, and resources supporting the entire product lifecycle from concept to disposal. Several systems are available to manage data and information during the lifecycle. A PLM system does not have to be considered as a unique solution, but as a set of software supporting different perspectives and activities related to the lifecycle management. A full comprehensive implementation of PLM systems is rare. Since PLM reflects the peculiarities of processes and data structures, implementation differences are evidently observable among companies. The design of methods and tools supporting an assessment of PLM implementation inside a company can enable a correct definition of PLM strategies and goals. Based on these premises, the paper aims to specify a methodology for carrying out a gap analysis of PLM with the scope of discovering existing technological and methodological gaps, and planning actions for improvement. The proposed methodology implements a visual and lean reference model, and an assessment questionnaire for data collection. Lesson learned and feedback from three industrial applications are also described and discussed.