Techniques for dynamically assigning acknowledgement (ACK) resource to a user equipment (UE) are described. For dynamic scheduling, a scheduling message may be used to send scheduling information for a single transmission of data. For semi-persistent scheduling, a scheduling message may be used to send a semi-persistent assignment for multiple transmissions of data. In an aspect, at least one field of a scheduling message, which is normally used to carry scheduling information for dynamic scheduling, may be re-used to carry an ACK resource assignment for semi-persistent scheduling. In one design, a UE may receive a scheduling message carrying a semi-persistent assignment and may obtain an assignment of ACK resource from the at least one field of the scheduling message. The UE may receive a transmission of data sent in accordance with the semi-persistent assignment, determine ACK information for the transmission of data, and send the ACK information with the ACK resource.