Considering background fluxes and D-branes in string theory leads to a deviation from standard Calabi-Yau compactifications. In this talk compactifications on non-Calabi-Yau orientifolds leading to a four-dimensional effective theory with N=1 supersymmetry will be discussed. Generalized complex geometry arises as the natural framework. Using the effective superpotential it is argued that also mirror symmetry in the presence of NS-NS flux leads to specific non-Calabi-Yau compactifications.