Medium accessing mechanisms within multiple user, multiple access, and/or MIMO wireless communications. A multi-user super-frame (MU-SF), as controlled by a MU-SF owner, is used to govern the manner by which various wireless communication devices have access to the communication medium. When various wireless communication devices operate within a wireless communication system, communication medium access can be handled differently for wireless communication devices having different capabilities. Per the MU-SF, those having a first capability may get medium access in accordance with a first operational mode (e.g., carrier sense multiple access/collision avoidance (CSMA/CA)), while those having a second capability may get medium access in accordance with a second operational mode (e.g., scheduled access). The respective durations for each of the first operational mode and the second operational mode within various MU-SFs need not be the same; the respective durations thereof may be adaptively modified based on any number considerations.