G. Dudek, N. Roy A rendezvous is a meeting between two or more agents at an appointed place and time, for example, when two people meet at a familiar restaurant. The problem of rendezvous is ubiquitous in nature. Migratory animals must be able to meet to share information about food. Non-social animals must be able to find each other during mating season. Humans are equally familiar with the problem of rendezvous, as any family whose members become separated at a large zoo or mall well knows. Multi-agent robot system also have an inherent need for meeting. We consider the problem of rendezvous between two robots exploring an unknown environment. That is, how can two autonomous exploring agents that cannot communicate with one another over long distances meet if they start exploring at different locations in an unknown environment. The intended application is collaborative map exploration. Ours is the first work to formalize the characteristics of the rendezvous problem, and we approach it by proposing several alternative algorithms that the robots could use in attempting to rendezvous quickly while continuing to explore. The algorithms are based on the assumption that potential rendezvous locations, called landmarks, can be selected by the robots as they explore; these locations are based on a distinctiveness measure computed with an arbitrary sensor.