PHIN Message Mapping Guides specify the content and structure of the NEDSS HL7 v2.5 message for case notifications submitted to CDC. The Message Mapping Guides are developed by the CDC programs working in collaboration with their analogous subject matter experts working in state and territorial health departments, they are reviewed by external partners, and subsequently published by CDC on the PHIN website. Staff from the Division of Integrated Surveillance Systems and Services (DISSS) in the National Center for Public Health Informatics recognize the need to explain the message mapping guides, what the NETSS-to-NEDSS transition is, and what this transition means for reporting jurisdictions interested in sending NNID case notifications to CDC. Also, Staff from DISSS have expertise in each aspect of this transition that external partners can utilize to adopt DISSS is currently collaborating and assisting states that have started to make this transition using HL7. DISSS has provided Rhapsody training for states that have adopted this tool to create the HL7 v2.5 message, assisted the states in mapping their state surveillance system variables to the disease-specific PHIN message mapping guide, and has guided the process of sending test and production case notification HL7 v2.5 messages to CDC via the Public Health Information Network – Messaging System (PHIN-MS).