The Delaware Historical Society Research Library offers the family historian a wide range of materials for research on Delaware families. Highlights include:
For a comprehensive introduction to family history resources see Delaware Genealogy: A Guide to Research at the Delaware Historical Society.
The Research Library also holds a good collection of general and how-to and genealogy books, and materials from east-coast states from New England to Virginia.
The Delaware Historical Society enjoys a close relationship with the Delaware Genealogical Society.