Formal models of business processes are used for a variety of purposes. But where the elicitation of the characteristics of a business process usually takes place in a collaborative fashion, the building of the final, formal process model is done mostly by a single person. This article presents the design and implementation of a Recommendation-Based Process Modeling Support System with ‘social features.’ A process builder using this system will receive recommendations to complete or edit a formal business process model on the basis of previous usage of modeling fragments by her peers. Such features potentially improve the modeling process and, as such, the modeling outcome, that is, the quality of the process model. This article also contains an evaluation of the system's usage and effectiveness, which builds on an experimental design. It is shown that process builders are inclined to follow up on the provided recommendations and that this will improve the semantical quality of the created model. However, information on peer usage of modeling fragments does not play a big role in selecting the recommendations being followed up. This article fits within a stream of research that puts emphasis on the modeling process, rather than on the model artifact.