This paper provides a roadmap for transitioning an existing production operation to one that fully implements a Lean manufacturing philosophy. Integration of engineering, human resources, and business viewpoints are incorporated into the roadmap to provide a systematic implementation process. Specific actions, in order of precedence, are organized into major phases with points of interface defined with other systems that are both internal and external to the business enterprise. Definitions of those terms used on the roadmap, which are unique in describing Lean activities and practices, are also presented in this paper. The roadmap is based upon experience gained to date by members of the Lean Aerospace Initiative in implementing Lean philosophy into production operations at various aerospace facilities and validated by research conducted by this Consortium at the Massachusetts Institute of Technology.