This thesis examines Iran's nuclear program and the cooperation and noncooperation between Iran and the IAEA. In recent years, Iran has always oscillated between compliance and defiance with regard to access control for IAEA inspectors and with regard to the information Iran itself provided to the IAEA on its nuclear program. At least since the United States unilaterally withdrew from the JCPOA in 2018, Iran's nuclear program has been reenergized with an eye toward military use. However, Iran largely still allowed IAEA inspections and even self-communicated information about them that clearly contradicted JCPOA regulations. In the thesis, neorealism, liberalism and constructivism are used to explain this behavior. It turns out that none of the grand theories alone can sufficiently explain the (non)cooperation between Iran and the IAEA. While liberalism offers some fruitful starting points, overall it has been shown that at least a theory combination is needed to holistically explain Iran's behavior with regard to the IAEA.