  I discuss D0-brane quantum mechanics as a nonperturbative formulation of
string theory, in particular the relation between the
Banks-Fischler-Shenker-Susskind matrix model, the Maldacena conjecture for
D0-branes, and type IIA/M-theory duality. Some features of the quantum
mechanics of D0-branes are also discussed. Lecture presented at the
Nishinomiya-Yukawa Memorial Symposium, Nov. 1998.
