The programEXPO2009is the evolution ofEXPO2004[Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004).J. Appl. Cryst.37, 1025–1028].EXPO2009performs all the steps ofab initiostructure solution by powder data: indexing, space-group determination, estimation of the reflection integrated intensities, structure solution by direct/Patterson methods and/or by a direct-space/hybrid approach, and model refinement by the Rietveld technique. New procedures have been introduced inEXPO2009for enhancing the structure solution process, particularly in the case of low-resolution data and/or organic compounds, when traditional approaches like direct methods may fail. TheEXPO2009graphical interface has been optimized and made very user friendly.