Pcons is a program for ranking protein models by assessing their quality. Users input a set of possible protein models which can, and should, be produced using various methods and approaches. The Pcons protocol analyzes the models and looks for recurring three-dimensional structural patterns. Each model is assigned a score reflecting how common its structural patterns are in the whole ensemble of models. The idea is that recurring patterns are more likely to be correct than patterns that only occur in just one or a few models.