Organizations build information systems to support their business processes. Precise modeling of an organization's processes is a prerequisite for building information systems that support those processes. Our goal is to help business analysts produce detailed models of the business processes that best reflect the needs of their organizations. To this end, we propose to a) leverage the best practices in terms of a kernel of generic business processes, and b) provide analysts with tools to customize those processes by generating new process variants. We use business patterns from the Resource Event Agent ontology to identify variation points, and to codify the transformations inherent in the generation of the process variants. We developed a prototype process specialization tool using the Eclipse modeling ecosystem. We tested our approach on a set of processes from the Enterprise Resource Planning literature, and a set of variation points to assess the extent to which: 1) the identified variation points made sense, and 2) whether the generated variants made sense, from a business point of view. The results showed that 94.12% of the variation points made sense, and that 80.6% of the generated process variants corresponded to what the business process management specialists expected.