When solids can be prepared only as microcrystalline powders and are not suitable for investigation by single crystal diffraction methods, it is necessary to elucidate structural properties directly from powder diffraction data. This article surveys some fundamental and applied aspects of an approach for solving crystal structures from powder diffraction data, in which Genetic Algorithm techniques are used to carry out global optimization (structure solution) on a hypersurface based on the powder profile R-factor. Examples are given to illustrate the application of the Genetic Algorithm technique in the case of molecular crystal structures.