Innovations often arise at the interface of different disciplines. The experimental environments, where these disciplines can find each other, are an ideal place to get started. However, cooperation must be facilitated, and there is an important role for the creative industries, which can bring together stakeholders and stimulate creativity and creation by means of co-creation and participation methods (see also Chapter 3). Unfortunately, the effectiveness of experiments in the described environments on policy change and transitions has not been sufficiently proven, and little is known about the sustainability of the environments. For example, what is needed to make the step from experiment to implementation? In addition, the interdisciplinary approach to experiments also leads to paradoxes, which result in a number of challenges and research questions that could be placed on the agenda for this KEM. We distilled a number of challenges, with related research questions. First, a number of practical questions with regard to the design and interaction between the participants in experimental environments, and finally a number of questions that focus on validity, and thus also link to other KEMs in this agenda, such as monitoring and effect measurement.