  We discuss the role of string solitons in duality and examine the feature of
compositeness, which allows for the interpretation of general solutions as
bound states of supersymmetric fundamental constituents. This feature lies at
the heart of the recent success of string theory in reproducing the
Bekenstein-Hawking black hole entropy formula. Talk given at 19th annual MRST
meeting, Syracuse, NY, May 12-13, 1997.
