Software Architecture has evolved from simple monolithic system designs to complex, multi-tiered, distributed, and componentized abstractions. Service-driven architectural approaches have been a major driver for enabling agile, cost-effective, flexible, and extensible software applications and integration solutions that support the business dynamics of today’s fast-paced enterprises. SOA and the SCA model have been the typical Service-driven architectural approaches used in enterprises today, to tackle the challenges of developing and implementing agile and loosely coupled software and enterprise integration solutions. Recent trends involve the use of Web APIs and RESTful architecture in the enterprise for agile service development and application integration. The goal of this chapter is to explore, discuss, and recommend methodologies for Service-driven Computing in the enterprise. Service versioning is detailed as a primary architectural approach for accommodating modifications to services during their life cycle. Service Mediation, Enterprise Service Bus, and Composition mechanisms including Enterprise Mashups are explored. The chapter also presents the business value of APIs in the enterprise and investigates the value-add to Social Media and Cloud enterprise initiatives. The typical phases of a Service-driven development life cycle are explained and service design patterns to facilitate the engineering of flexible service-based applications are described. The chapter concludes with thoughts on future opportunities and challenges in the area of Service-driven computing.