The integrator integrates the system, in accordance with the integration build plan, by adding the delivered implementation subsystems into the system integration workspace and creating builds. Each build is then integration tested by a tester. After the last increment, the build can be completely system tested by a tester.

Integration is typically carried out by a single person (for a small project on which the build process in simple) or a small team (for a large project on which the build process is complex). The integrators need experience in software build management, configuration management, and experience in the programming language in which the components to be integrated are written. Because integration often involves a high degree of automation, expertise in operating system shell or scripting languages and tools like 'make' (on Unix) or 'ant' (for Java) is also essential.