- Alameda County GenWeb - Part of the California GenWeb Project.
- Alameda County Historical Society - Holds quarterly dinner meetings and conducts field trips; publishes Alameda County Historical Society Quarterly; conducts ongoing preservation programs.
- Hayward Area Genealogical Society - Meets monthly from January through October on the fourth Tuesday, 6:30 - 8 p.m. in the San Lorenzo Library, 395 Paseo Grande (you don't have to be a member to attend). The society publishes a monthly newsletter, The Informer, from January through November. H.A.G.S., PO Box 754, Hayward 94543, or call Carl Webb at 351-3335.
- Hayward Area Historical Society - Preserves Hayward history, including San Lorenzo. Operates a museum, library, and bookstore ( 22380 Foothill Blvd., Hayward), as well as the restored McConaghy Estate, a private residence built in 1886 (on Hesperian Boulevard near Bockman Road). The Society holds regular meetings and social functions and publishes a quarterly magazine, "Adobe Trails," which contains articles on local history. Local residents are encouraged to join. Call 581-0223.
- Museum of Local History - The historical archives of neighboring Washington Township, which includes the cities of Fremont, Union City, and Newark.
- Muwekma Ohlone Tribe of the San Francisco Bay Area - The tribe is composed of all the known surviving American Indian lineages aboriginal to the San Francisco Bay region. The website is rich in description and imagery of Ohlone history and culture.
- San Leandro Historical Society
- San Leandro History Room (San Leandro City Library) - The collection includes more than 7,000 volumes as well as numerous photographs and documents. For information call the library information desk at 510.577.3971.
- San Lorenzo Express - A central source of information on present-day San Lorenzo.
- Save the Lorenzo - The Lorenzo Theater Foundation promotes restoration of the theater. The theater was purchased by the former Alameda County Redevelopment Agency