We study the large volume limit of the scalar potential in Calabi-Yau flux
compactifications of type IIB string theory. Under general circumstances there
exists a limit in which the potential approaches zero from below, with an
associated non-supersymmetric AdS minimum at exponentially large volume. Both
this and its de Sitter uplift are tachyon-free, thereby fixing all Kahler and
complex structure moduli, which has been difficult to achieve in the KKLT
scenario. Also, for the class of vacua described in this paper, the gravitino
mass is independent of the flux discretuum, whereas the ratio of the string
scale to the 4d Planck scale is hierarchically small but flux dependent. The
inclusion of alpha' corrections plays a crucial role in the structure of the
potential. We illustrate these ideas through explicit computations for a
particular Calabi-Yau manifold.
