Census data is distributed in specific geographies, such as census block groups and census tracts. It is common for researchers to have study areas that do not correspond to these predetermined geographies. This workshop will teach participants how to determine more accurately the demographics of a custom study area, through the implementation of a Cadastral-based Expert Dasymetric System (Maantay et al., 2005). This system disaggregates demographics from census block groups and reaggregates it in new geographic areas, taking into account land use and distribution of residential units.