The way we interact with media has changed. Devices such as laptops, phones and tablets now supplement television watching for many. This behaviour allows viewers to engage more deeply with, or engage with content unrelated to, the television content they are simultaneously watching. This leads to the possibility of leveraging devices in a living room to deliver a synchronous, holistic experience over two screens: a companion screen experience. Although some examples of commercial companion screen experiences have been attempted, few have offered a genuinely enhanced experience to audiences. This thesis examines how it is possible to design experiences that truly add value to a television experience, asking the central research question, how should companion screen experiences be designed?A number of companion screen experiences are developed and evaluated. A comparison chapter discerns how using the space around a TV to deliver a companion experience impacts a users experience when compared to a companion experience delivered more traditionally on a tablet.This leads to a more thorough investigation of the orchestration of companion experiences, addressed by using the novel approach of involving television professionals and audience members in the very initial stages of developing a companion screen experience, as a way of generating design guideline[s] for a companion experience. A potential guideline is uncovered for further investigation in the form of a hypothesis for testing. This hypothesis is then put under test in order to rigorously validate this design guideline for producers and designers of companion screen experiences. This rigorously-validated design guideline then leads to an important implication for broadcasters when it comes to providing and producing companion screen experiences.A final contribution of this research is the many potential directions for future research that the thesis yields.