Quantitative determination of phase abundance in a multicomponent polycrystalline mixture is a basic goal in materials characterization. Because of several advantages compared with traditional techniques, the Rietveld method has been increasingly applied to this task. Further progress in this direction would be to carry out the analysis automatically. The new Rietveld packageQuantois devoted to the automatic estimation of the weight fraction of each crystalline phase in a mixture. The amorphous content can be estimated by means of the internal-standard method. Corrections for preferred orientation and microabsorption effects are available. A user-friendly graphical interface facilitates interaction. A data bank including several organic and inorganic phases is supplied with the program.