Though it is widely recognized that people with intellectual and developmental disabilities (IDD) face significant health disparities, the comprehensive data sets needed for population-level health surveillance of people with IDD are lacking. This paucity of data makes it difficult to track and accurately describe health differences, improvements, and changes in access. Many states maintain administrative health databases that, to date, have not been widely used for research purposes. In order to evaluate the feasibility of using administrative databases for research purposes, the authors attempted to validate Massachusetts' administrative health database by comparing it to a large safety net hospital system's patient data regarding cancer screening, and to the state's service enrollment tables. The authors found variable representativeness overall; the sub-population of adults who live in 24-hr supported residences were better represented than adults who live independently or with family members. They also found a fairly low false negative rate for cancer screening data as compared with the “gold standard” of hospital records. Despite some limitations, these results suggest that state-level administrative databases may represent an exciting new avenue for health research. These results should lend context to efforts to study cancer and health screening variables using administrative databases. The present study methods may also have utility to researchers in other states for critically evaluating other state IDD service databases. This type of evaluation can assist researchers in contextualizing their data, and in tailoring their research questions to the abilities and limitations of this kind of database.