String dualities from Matrix theory

We suggest that the (2,0) six-dimensional field theory compactified on S¹ × K3 is the Matrix model description of both M-theory on K3 and the heterotic string on T³. This proposal is different from existing proposals for the heterotic theory. Different limits of the base-space geometry give the different space-time interpretations, making M-theory/heterotic duality manifest. We also present partial results on heterotic/F-theory duality.