Method and apparatus for multiplexing data for multiple wireless transmit/receive units (WTRUs) for high speed downlink channels are disclosed. A WTRU may receive a joint high speed shared control channel (HS-SCCH) including a common part and WTRU-specific parts. The common part includes common control information for WTRUs multiplexed in one transmission time interval (TTI), and each of the WTRU-specific parts includes WTRU-specific control information for a corresponding WTRU. The WTRU receives a high speed physical downlink shared channel (HS-PDSCH) based on decoding on the joint HS-SCCH. The HS-SCCH may include a group WTRU identity shared by a group of WTRUs.