Folding of proteins from the denatured to native state is a very complex dynamical process. In recent years it has become clear that one cannot define a single pathway in the ordinary sense of chemical reactions, but that a proper description of folding must involve a multitude of pathways defining various transition state ensembles which help to nucleate the folding process. Time-resolved small-angle x-ray scattering data will be presented which demonstrate the diversity of folding processes for different small proteins. A new approach to computer simulation of the folding process at atomic resolution will be presented in which the statistics of different folding pathways is sampled by reaction path annealing.