- Most reference models do not explicitly guide their reuse process. However, they are all designed according to (at least) an implicit intended reuse process. An important type of reuse is specialization, which allows a high level of flexibility and variability when instantiating reference models to specific business processes. In this paper we propose an approach that facilitates reuse by specialization by using a domain engineering approach called ADOM. We identify five possible specialization operations, namely refinement, sub- typing, contextual adoption, omission, and inclusion, discuss their essence, and exemplify their usage within ADOM. These operations and their application within ADOM may provide a significant improvement in business process design while leveraging existing business process reference models.