A method and apparatus for neighbor discovery in a wireless communication system are disclosed. A neighbor seeking wireless transmit/receive unit (WTRU) may send a first beacon based on configuration information provided by the network. The neighbor WTRUs receive the first beacon and may send either a report to the network or send a second beacon to the neighbor seeking WTRU. The network may then provide neighbor WTRU information to the neighbor seeking WTRU. The neighbor discovery may be performed within a pre-defined group of WTRUs that is formed based on proximity to the WTRU and/or an attribute of the WTRU. The neighbor discovery procedure may be performed to find neighbor WTRUs in case where a WTRU fails to find any network. A neighbor list may be generated by the neighbor seeking WTRU by measuring reference signals transmitted by neighbor WTRUs on an uplink to the network.