Niklas Luhmann is known for having developed a broadly applicable theory of power that demonstrates how power dynamics depend on social structures and, in particular, on forms of differentiation, and how they change along with them. "Power in the System" was created in the late 1960s and reflects the significance of the topic in Luhmann's early work. Unlike in later versions of his power theory, he argues here more from a systems theory perspective rather than a communication theory perspective. Thus, "Power in the System" is also an insightful document of the evolving system theory.