The Upper Darby Historical Society was founded in 1984 for the purpose of preserving historic sites, documents, monuments, and artifacts in Upper Darby Township, Delaware County, Pennsylvania. The Society holds about 60 linear feet of archival materials, one-third of which consists of a set of approximately 1,000 early 1900s glass plate negatives from a local photographer. The remainder of the Society's archival holdings consist of various primary and secondary source materials dating from 1799 to 2013 that document Upper Darby families, individuals, organizations, institutions, and events over time. The primary source materials include maps, scrapbooks, deeds, photographs, slides, ephemera, correspondence, autograph books, and more; the secondary source materials include newspaper clippings, photocopies of original documents, narrative histories, research notes, and printed works.