Complexity theory may refer to:
Theories Computational complexity theory, a field in theoretical computer science and mathematics Assembly theory, to quantify the complexity of molecules and objects
Complex systems Complex systems, describing systems of many interacting parts Complex adaptive system, a special case of complex systems
Complexity economics, the application of complex systems to economics Complexity theory and organizations, the application of complex systems to strategy
See also Computational complexity Complexity
Complexity (disambiguation) Systems theory Systems thinking Complex network