Systems and methods are disclosed for collaborative authentication of a person based on an interaction with another person. A request for collaborative authentication is sent to the computing device of a person wanting to access a system, including an authentication ID unique to the request. The person collaborates with another person associated with the system and provides the second person with the authentication ID. The second person sends the authentication ID to the system such that the system associates the second person with the first person. Data is sent to the second person in order to challenge the first person. The first person responds to the challenge using the computing device and the system receives the response. The system compares the response to an expected answer and can either allow or deny the first person access to the system based on the comparison. Co-location may also be verified.