A method and system for reporting evolved universal mobile telecommunication systems (UMTS) terrestrial radio access network (E-UTRAN) capabilities are disclosed. A wireless transmit/receive unit (WTRU) sends a first message to a core network (CN) to report the E-UTRAN capabilities of the WTRU. The CN then updates the WTRU capabilities based on the first message. The first message may include a radio access capability information element (IE) which carries information related to E-UTRAN capabilities of the WTRU and/or a network capability IE which carries information regarding network capabilities of the WTRU. The CN may send a second message to the WTRU to report network capabilities with respect to the radio access networks (RANs) to which the core network is connected and services that can be provided over the E-UTRAN.