A method and apparatus for uplink feedback for operating with a large number of carriers are disclosed herein. A method in a wireless transmit/receive unit (WTRU) includes receiving a plurality of transport blocks over a set of a plurality of configured carriers, generating hybrid automatic repeat request (HARQ)-acknowledgment (ACK) feedback for the transport blocks and determining a number of HARQ-ACK feedback bits to use for the HARQ-ACK feedback. Further, the WTRU may apply, to the HARQ-ACK feedback bits, Reed-Muller coding on a condition that the number of HARQ-ACK feedback bits is less than or equal to a threshold or convolutional coding on a condition that the number of HARQ-ACK feedback bits is greater than a threshold. The WTRU may then transmit the encoded HARQ-ACK feedback bits. In addition, the WTRU may conditionally append cyclic redundancy check (CRC) bits onto the HARQ-ACK feedback bits, and encode and transmit the CRC bits.