A method and apparatus for neighbor discovery in a wireless communication system are disclosed. A neighbor seeking wireless transmit/receive unit (WTRU) may search for a first signal to discover neighbor WTRUs for peer-to-peer communication. The WTRU may then receive the first signal. Further, the WTRU may generate a report based on the received first signal. Then, the WTRU may send a second signal carrying the report to a cellular wireless network. The first signal may include a beacon for neighbor discovery or a synchronization signal or both. The report may contain at least one neighbor WTRU identity or at least a portion of a time value or both. Further, the report may contain a counter value, including at least a portion of a time value. The counter value may be based on a time source. In addition, the first signal may be received from a synchronization source.