PI TAU SIGMA members are chosen on a basis of sound engineering ability, scholarship (upper 35%), personality, and probable future success in their chosen field of Mechanical Engineering. There are three grades of membership: Honorary, Graduate, and Active. Honorary members are technical graduates actively engaged in engineering work; or members of mechanical engineering faculties. Graduate membership is conferred upon persons who would have been eligible had Pi Tau Sigma been established earlier in schools not having chapters, or upon those continuing graduate study. Active members are selected from the junior and senior mechanical engineering classes at their respective schools whose mechanical engineering curriculum must be accredited by ABET.