Service-oriented architecture (SOA) embodies a set of principles including service abstraction, composability, discoverability, and reusability, among others. Although these principles are widely circulated by SOA technology vendors, there have been few efforts to collect, organize, and elaborate on these principles for the purpose of guiding system design. This chapter explores how service-oriented design principles can be organized in a goal-graph representation complementary to original text and used in system design. The approach builds upon the NFR framework for treating non-functional requirements in software engineering. The chapter proposes a method to extract SOA design principles from textually represented service-oriented knowledge sources. The method is applied to an SOA knowledge source, extract an SOA design knowledge-base organized by design principles and presented by goal-graphs, and the chapter then explores application of such knowledge-base.