This collection includes correspondence, brochures, newsclippings, papers, and copies of historical documents related to the Rancho San Pedro. Subjects include the Dominguez Adobe and Claretian Seminary, families descended from the Dominguez sisters, companies owned by these descendants, and the history of the Rancho San Pedro.

This collection includes correspondence, legal documents, tax documents, and bonds created by the Title Insurance and Trust Company. These materials are related to trusts held by members of the Dominguez family and land that was once part of the Rancho San Pedro.