Mobile Bay National Estuary Program (MBNEP) requested an assessment of the accuracy of National Land Cover Data 2001 (NLCD 2001, compiled by the Multi-Resolution Land Characteristics Consortium) as compared to National Wetlands Inventory (NWI (Cowardin and others, 1979), to include uplands through incorporation of modified Anderson Level III definitions (Anderson and others, 1976)) mapping of Mobile and Baldwin Counties conducted by the U.S. Geological Surveys (USGS) National Wetlands Research Center (NWRC). Both classifications were checked against stratified randomly selected ground-based sites and with each other to compare the accuracy of the NLCD with NWI classification methods. Previous to this comparison, we conducted an accuracy assessment of the modified NWI in Louisiana with an overall accuracy of 93 percent (Handley and others, 1995). For this accuracy comparison, numerous visits were made by photointerpreters to the Mobile Bay area to establish signatures for the modified NWI mapping. After all of the quadrangles in Baldwin and Mobile Counties were mapped, an accuracy assessment of those maps was conducted by field-checking the mapped classes with ground-based check sites. These same sites were used to check the accuracy of the NLCD and also as the basis for cross-walking the NLCD and NWI classification systems for direct comparison of the two methods. This accuracy assessment focused on the latest of several dates of habitat mapping projects of the Mobile Bay area by NWRC using the same photointerpretation methodology and classification system. We have used this methodology and NWI classification on numerous other dates and regions. Extrapolation beyond this data set is appropriate for maps of the same methodology and classification of the Mobile Bay region. This accuracy assessment provides analytical information about the classification accuracy of 2001/2002 NWI classification and the 2001 NLCD classification.