  We address the derivation of the effective conformal field theory description
of the 5-dimensional black hole, modelled by a collection of D1- and D5-
branes, from the corresponding low energy U(Q_1)xU(Q_5) gauge theory. Finite
horizon size at weak coupling requires both Q_1 and Q_5 to be large. We derive
the result in the moduli space approximation (say for Q_1>Q_5) and appeal to
supersymmetry to argue its validity beyond weak coupling. As a result of a
combination of quenched Z_{Q_1} Wilson lines and a residual Weyl symmetry, the
low-lying excitations of the U(Q_1)xU(Q_5) gauge theory are described by an
effective N=4 superconformal field theory with c=6 in 1+1 dimensions, where the
space is a circle of radius RQ_1Q_5. We also discuss the appearance of a
marginal perturbation of the effective conformal field theory for large but
finite values of Q_5.
