Third International Atmospheric Circulation Reconstructions Over the Earth Initiative Workshop: Reanalysis and Applications; Baltimore, Maryland, 3–5 November 2010; The third Atmospheric Circulation Reconstructions over the Earth (ACRE) workshop advanced the goals of the international ACRE initiative (http://www.met-acre.org/) to undertake and facilitate the recovery of instrumental terrestrial and marine global surface weather observations underpinning global weather reconstructions and reanalyses spanning the past 200–250 years (http://reanalyses.org). The workshop improved integration of the 35–40 ACRE-linked international scientific projects, institutions, and organizations working toward these ends. The meeting highlighted the broad array and international usage of ACRE-facilitated data sets and reanalysis: the International Surface Pressure Databank (ISPD; http://dss.ucar.edu/datasets/ds132.0/), the International Comprehensive Ocean-Atmosphere Data Set (http:/icoads.noaa.gov/ICOADS;), and the 20th Century Reanalysis (20CR; http://www.esrl.noaa.gov/psd/data/20thC_Rean/). The need for more data recovery for all regions of the globe during the nineteenth and early twentieth centuries was emphasized. Many regional efforts for such recovery are under way. The Arctic and maritime regions were highlighted as particular areas needing attention. As a result of the meeting, connections with existing projects were made and new efforts were started to address these needs.