The NOAA CPO Modeling, Analysis, Predictions, and Projections (MAPP) program hosted a technical workshop for the NOAA Climate Reanalysis Task Force (NCRTF) on May 4-5, 2015 at the NOAA Center for Weather and Climate Prediction (NCWCP) Conference Center in College Park, Maryland. The NCRTF is an initiative of the MAPP program intended to facilitate coordination among relevant MAPP-funded research efforts to help advance NOAA’s climate reanalysis and data assimilation capabilities. Reanalyses combine observations covering the full instrumental record of each component of the Earth system and are essential to the monitoring and prediction of both weather and climate. For more information about the workshop, go to: http://cpo.noaa.gov/