Theory of Constraints is a highly regarded management innovation that runs contrary to conventional wisdom. TOC is best known in the Manufacturing and Distribution sectors where it originated, but services are the dominant sectors in most economies nowadays. The Professional, Scientific, and Technical Services (PSTS) sector is notable because many of its services are not repeatable, thereby making TOC much harder to apply. Nevertheless, it can be done. This chapter summarizes how and why TOC has been adapted for PSTS. It includes applications for management of resources, projects, business processes, accounting, marketing, sales, strategy, and implementation. Among the benefits of TOC are faster services, greater flexibility, and a sensible re-shuffling of management priorities for profitable growth. Simply stated, TOC makes constraints work for you rather than against you. This chapter explains how practitioners can get started with TOC for services, what researchers can contribute, and what students should know.