In this chapter the general principle of adaptive combination tests is applied to two important situations in clinical trial. The first is the design with multiple treatment arms where, based on interim results, one or more arms are selected. The second is the design where one or more pre-specified subsets of a population are selected for further investigation, the latter designs are called ... [Show full abstract] adaptive enrichment designs. The combination testing principle together with the closed testing principle can be used in both settings. We will describe the procedures in detail, particularly, which intersection tests can be used for specific situations and provide examples for the assessment of these designs. We also provide real trial examples to illustrate how these designs were used in practice. We then discuss other types of adaptations that were discussed in the literature. In the last section of this chapter, we briefly discuss the added logistical and regulatory complexity when performing adaptive designs.