The Permafrost Carbon Network (www.permafrostcarbon.org) held another successful workshop for synthesis leads and co-leads in Flagstaff, AZ, USA (May 11-12, 2015). The objectives of this workshop were to bring together leading scientists of the Permafrost Carbon Network to discuss and plan new synthesis products. One particular focus of this meeting was to advance model development by exploring benchmarking tools that can be provided by field and lab based scientists along with finalized model output from the Permafrost Carbon Model Intercomparison Project that estimates the permafrost carbon climate feedback for this century and beyond. In advance of the workshop, participants prepared scoping papers that contained details about the new syntheses. The majority of the workshop was used to discuss and refine these newly proposed synthesis activities as a group and to outline best strategies for ways forward. The follow-up activities of this workshop are outlined in individual scoping documents, which are shared with members of the Permafrost Carbon Network through our website. Upcoming, we will have short presentations during our 5th Annual Meeting of the Permafrost Carbon Network at AGU in December of 2015, where brief updates about the progress of individual synthesis activities will be given to the larger community of scientists. The workshop in Flagstaff, AZ was sponsored by the National Science Foundation, Climate and Cryosphere (CliC) and contributions from individual participants.