FDA is committed to provide guidance for industry on adaptive design clinical trials. In this presentation, I will lay out the principles of adaptive design trials in early versus late phase of a drug development program. A variety of design elements eligible for adaptation considerations will be discussed using examples ranging from adaptive dose ranging designs to treatment regimen, primary endpoint, and patient population adaptations that often comes with sample size adaptation. Design issues on flexibility versus efficiency, analysis approaches using frequentists versus Bayesian approaches, and the clinical rationales prompting adaptive design proposals will be highlighted and illustrated using case examples in the context of treatment indication. Guidance on statistical validity, trial integrity, results reporting and interpretability will also be addressed.