Abstract: A contact sharing system is described herein that allows multiple people to share their address books of contact information so that a person can search for contact information among the address books of the person's existing contacts in addition to any publicly available searchable sources of contact information. Because at least one of a person's contacts is likely to have contact information for the person or business that the person is trying to reach, searching the contacts of contacts is more likely to produce relevant search results than searching anonymous or public sources of contact information alone. Thus, the contact sharing system makes it easier for people to find contact information for people and businesses that they are trying to reach.