At the National Climatic Data Center, two basic approaches to making homogeneity adjustments to climate data have been developed. The first is based on the use of metadata (station history files) and is used in the adjustments made to the U.S. Historical Climatology Network monthly dataset. The second approach is non-metadata based and was developed for use with the Global Historical Climatology Network dataset, since there are not extensive station history files for most stations in the dataset. In this paper the two methodologies are reviewed and the adjustments made using each are compared, then the results are discussed. Last, some brief guidelines on the limitations and uses of these data are provided.