Resources housed here include Sacramental Records and Registers. Their collection is limited to:
"...parishes within the current boundaries of the Archdiocese of Baltimore (est. 1789), which is comprised of the following counties: Allegany, Anne Arundel, Baltimore, Baltimore City, Carroll, Frederick, Garrett, Harford, Howard, and Washington. Records for parishes that now comprise the Archdiocese of Washington, DC (est. 1939), Diocese of Wilmington, DE(est. 1868), Diocese of Richmond (est. 1820), and Diocese of Wheeling-Charleston (est. 1850) can only be accessed through those respective dioceses."
Check their website for more information about genealogical requests and materials available, including guides.