Knowledge of the distribution of solar energy at the earth's surface is required for various practical and theoretical purposes. The solar fluxes calculated in Re-Analysis projects are promising since their radiative transfer calculations take into account the best current estimates of the humidity and temperature structure in the atmosphere. The present study assesses the quality of the insolation climatology of the ECMWF Re-Analysis (ERA) using a comprehensive set of surface observations. It is shown that the ERA surface insolation climatology is in good agreement with more than 700 long-term monitoring sites. The biases are substantially smaller than generally found in GCMs, which typically overestimate the surface insolation due to an underestimated atmospheric shortwave absorption. Contributing to the quality of the ERA insolation climatology is not only the realistic structure of the overlying atmosphere, but also the accurate performance of the radiation scheme under clear-sky conditions. This is shown in off-line calculations with the ERA radiation scheme using prescribed atmospheric profiles from radiosondes as input. Overall, the paper suggests that the ERA reproduces the global distribution of solar energy at the surface with considerable skill and that the ERA insolation climatology may be useful for various applications. ¿ 1998 American Geophysical Union