On the 14th of June I successfully defended my doctoral thesis Toward Robust Optimization of Adaptive Radiation Therapy. Adaptive radiation therapy is an evolving treatment method in which the treatment plan is adapted in response to patient-specific geometric variations. In this thesis, a variety of robust optimization approaches are combined with the concept of adapstive radiation therapy. This combination allows to adapt the treatment plans to the specific variations experienced by the individual patient. A variety of mathematical frameworks are presented and evaluated in this thesis. This contributes to a better understanding of the underlying mechanisms between robustness, the adaptive strategies and the optimized dose profiles. The findings of this thesis are intended to provide a mathematical foundation for further development of the framework for, and research on, robust optimization of adaptive radiation therapy toward a clinical setting.