Unlike the structural generalization practice, the structural specification method advocates dissecting a service into smaller and more manageable units of analysis. This process introduces a set of best practices devised to facilitate decomposition, retirement, substitution, or swapping of service capabilities. Structural specification is also about source code, design, and architecture refactoring. The term “refactoring” pertains to the enhancement of a service structure by analysing first its internal formation to propose a better architecture solution and improve performance and reuse. Additionally, the refactoring process may be pursued to update a service's dated capabilities and technologies or to swap aggregated services between two or more containing entities, such as composite services and service clusters. This chapter introduces varied methods and affiliated patterns that can assist practitioners with service decomposition and internal service component manipulation to optimize service capabilities.