Psychologists can now quantify behaviours beyond the laboratory using a mass-adopted, unified system that is primed for data capture a.k.a. smartphones. This is the first book to bring together related areas of smartphone research and point towards how psychology can benefit and engage with these developments in the future. It critically considers how smartphones and related digital devices help answer and generate new research questions for psychological science. The book then guides readers through how smartphones are being used within psychology and social science more broadly. Drawing from examples of both good and bad practice within current research, a new perspective is brought to major themes and debates across behavioural science. In the digital age, smartphones and associated devices will be able to accomplish much more in the near future. Psychology has a key role to play when it comes to balancing this monumental potential with carefully considered research.