In recent years the need for accessing historical Earth Observation data information has greatly increased, driven by long term scientific and environmental monitoring. The need to preserve such data indefinitely has led to the establishment of the Long-Term Data Preservation (LTDP) guidelines for Earth Observation. However to make full use of this data, it is necessary to have sufficient quality information available to be assured about the data quality. This is the objective of the Quality Assurance for Earth Observation (QA4EO) framework developed by the CEOS Working Group on Calibration and Validation (CEOS WGCV).