  We show that Type IIB string theory on AdS_3 X S^3 X M_4 with p units of NS
flux contains an integrable subsector, isomorphic to the minimal (p,1) bosonic
string. To this end, we construct a topological string theory with target space
Euclidean AdS_3 X S^3. We use a variant of Hamiltonian reduction to prove its
equivalence to the minimal (p,1) string. The topological theory is then
embedded in the physical ten-dimensional IIB string theory. Correlators of
tachyons in the minimal string are mapped to correlators of spacetime chiral
primaries in the IIB theory, in the presence of background 5-form RR flux. We
also uncover a ground ring structure in AdS_3 X S^3 analogous to the well-known
ground ring of the minimal string. This tractable model provides a literal
incarnation of the idea that the holographic direction of AdS space is the
Liouville field. We discuss a few generalizations, in particular we show that
the N=4 topological string on an A_{p-1} ALE singularity also reduces to the
(p,1) minimal string.
