Adaptive designs and complex clinical trials offer many well-known advantages throughout the clinical development process and their acceptance is steadily increasing. Typically, such designs use either the Bayesian or the frequent framework for decision making and reporting. While frequentist adaptive designs often have closed-form calculations of operating characteristics, Bayesian designs usually require simulations. On the other hand, Bayesian designs often make it easy to communicate results, incorporate multiple endpoints and achieve efficiency gains by using e.g., the predictive probability for interim decision making. Regardless of the choice of analysis method and the associated philosophical differences in the paradigms, there is an understanding that, among others, frequentist operating characteristics such as power and type 1 error are important to evaluate the proposed design. Ultimately, both Bayesian and frequentist adaptive designs aim to and should be judged by their ability to produce better and more efficient clinical trials without compromising their statistical integrity. In this session, we will bring together experts in the design of both Bayesian and frequentist adaptive trials, as well as a senior European regulator to learn more about recent methodological advances, regulatory considerations, and practical experiences when designing and assessing these trial designs.