This paper is a high-level guide to inform National Communications System (NCS) member agencies that will be implementing the current version of the Defense Message System (DMS). Normally, DMS is implemented by transitioning from the Automatic Digital Network (AUTODIN) or via an upgrade from an earlier version of DMS. Organizations need to determine whether they will be adopting or upgrading DMS. If an agency is required to do so, then this paper will assist in the process of adopting or upgrading DMS. The first section of the guide presents a brief background on AUTODIN and DMS, including a summary of the status of DMS implementation and a description of how DMS messages are transmitted. The second section covers key steps and recommendations for implementing DMS. The guide also offers several appendixes, including a detailed step-by-step plan for transitioning from AUTODIN to DMS, a guide for upgrading from earlier versions of DMS, and a tutorial on DMS security services.