Master

Jedi Academy Knights and above are allowed to take on official Padawans. Their is no maximum amount of Padawans a Knight (or above) may have, however, most Knights only take on so many at once. The advantage of having a Master, is that you can attend Padawan Sessions, and get 1 on 1 training from that person, this is especially useful when you cannot attend Classes.

Jedi Academy Students can take on Padawans aswell, but they will not be official.