A method, implemented by a first responder device (1110, 1120, 1130, 1140), as one of a plurality of responder devices (1110, 1120, 1130, 1140), the method comprising: receiving, by the first responder device from an initiator device, a message frame containing scheduling information that announces a training period and a feedback period for multiple-input-multiple-output, MIMO, beamforming training; receiving, by the first responder device from the initiator device, at least one training frame, each respective training frame having a plurality of training sequences appended to an end of the respective training frame, wherein each training frame is sequentially transmitted using a respective transmit beam of a plurality of transmit beams, and wherein a number of training sequences is representative of a number of receive beams of the plurality of responder devices to be trained; for each training frame, sequentially receiving, by the first responder device, on each of a plurality of receive beams during the training sequences; determining, by the first responder device, a best transmit beam of Z the plurality of transmit beams of the initiator device; determining, by the first responder device, a best receive beam of the plurality of receive beams of the first responder device that are trained using the plurality of the training sequences; selecting, by the first responder device, one of a plurality of feedback period time slots in which to transmit based on a receive beam of the initiator device corresponding to the best transmit beam of the initiator device; transmitting, by the first responder device to the initiator device, a beamforming-feedback response during the selected feedback period time slot associated with the receive beams of the initiator device in the announced feedback period, wherein the announced feedback period is a contention-based feedback period such that the first responder device and at least one other responder device have contending beamforming-feedback responses during the selected feedback period time slot within the announced feedback period, and wherein the beamforming-feedback response is transmitted on a transmit beam of the first responder device that is associated with the best receive beam of the first responder device; and receiving, by the first responder device from the initiator device, at least one acknowledgment frame. receiving, by the first responder device from an initiator device, a message frame containing scheduling information that announces a training period and a feedback period for multiple-input-multiple-output, MIMO, beamforming training; receiving, by the first responder device from the initiator device, at least one training frame, each respective training frame having a plurality of training sequences appended to an end of the respective training frame, wherein each training frame is sequentially transmitted using a respective transmit beam of a plurality of transmit beams, and wherein a number of training sequences is representative of a number of receive beams of the plurality of responder devices to be trained; for each training frame, sequentially receiving, by the first responder device, on each of a plurality of receive beams during the training sequences; determining, by the first responder device, a best transmit beam of Z the plurality of transmit beams of the initiator device; determining, by the first responder device, a best receive beam of the plurality of receive beams of the first responder device that are trained using the plurality of the training sequences; selecting, by the first responder device, one of a plurality of feedback period time slots in which to transmit based on a receive beam of the initiator device corresponding to the best transmit beam of the initiator device; transmitting, by the first responder device to the initiator device, a beamforming-feedback response during the selected feedback period time slot associated with the receive beams of the initiator device in the announced feedback period, wherein the announced feedback period is a contention-based feedback period such that the first responder device and at least one other responder device have contending beamforming-feedback responses during the selected feedback period time slot within the announced feedback period, and wherein the beamforming-feedback response is transmitted on a transmit beam of the first responder device that is associated with the best receive beam of the first responder device; and receiving, by the first responder device from the initiator device, at least one acknowledgment frame.