Many of today's languages used in software engineering have bad built-in support for software composition. It is important for software engineering to provide languages and tools to define, reuse and compose software components. Still, many languages available today for programming, modeling, markup, scripting and rule writing do not support a proper way of defining components. They do not include concepts about how to compose components and thus there are no tools for these languages to execute compositions. Invasive Software Composition offers generic composition concepts that can be injected into arbitrary languages. This book introduces an EBNF and MOF-based metamodeling approach through which languages can be extended with Invasive Software Composition concepts. It describes the architecture of the Eclipse Component Model Generator: a tool built on modern technology such as the Eclipse Modeling Framework and the Eclipse Platform. The book demonstrates on different examples how components are defined and compositions are executed with the tool. This book targets software engineers, researchers and students interested in modern software composition and metamodeling techniques.