This book outlines a structured progression for implementing Service Integration and Management (SIAM) within complex, multi-vendor environments. It begins by defining SIAM principles, roles, layers, and structural models to establish a shared understanding of its purpose and scope. The roadmap then unfolds in four key stages. The Discovery & Strategy phase focuses on analyzing the current state, setting strategic drivers, and establishing governance foundations. In Plan & Build, the book guides readers through designing the SIAM model, sourcing structures, contracts, and process frameworks. The Implement stage addresses onboarding, transition planning, and applying change management across stakeholder groups. Finally, Run & Improve centers on operating the governance model, managing performance, conducting audits, and enabling continuous service development. Each chapter links practical methods with decision-making considerations, offering a reference for teams planning, launching, or refining a SIAM approach. The content is organized to support structured adoption while allowing flexibility for varied organizational contexts.