A discipline is one of six groupings of powers, each defined by a common theme. The six disciplines are clairsentience, metacreativity, psychokinesis, psychometabolism, psychoportation, and telepathy. If a psion chooses to specialize in a discipline, he gains special benefits, while those who choose to stay generalists gain unique benefits of their own.
Psions of a particular discipline can chose to focus their studies still further within that discipline. Psions who choose an advanced discipline gain all the normal benefits of their discipline, but the advanced discipline changes one or more of the abilities granted by their advanced discipline. A psion must take all of the replacement abilities associated with his advanced discipline. Once an advanced discipline is chosen, it cannot be changed.