  We show that an earlier domain wall solution of type IIB supergravity
provides a supersymmetric realization of the Randall-Sundrum brane-world, and
give its ten-dimensional interpretation in terms of IIB 3-branes. We also
explain how previous no-go theorems are circumvented. In particular, whereas
D=5 supergravity scalars have AdS_5 energy E_0 <= 4 and are unable to support a
D=5 positive tension brane, our scalar has E_0=8, and is the breathing mode of
the S^5 compactification. Another essential element of the construction is the
implementation of a Z_2 symmetry by patching together compactifications with
opposite signs for their 5-form field strengths. This is thus a IIB analogue of
a previous D=5 3-brane realization of the Horava-Witten orbifold. A
mode-locking phenomenon avoids the appearance of negative energy zero-modes in
spite of the necessity of a D=10 negative tension brane-source.
