The set of techniques known collectively as real-time data capture (RTDC) is becoming increasingly important in medical research. Based on the collection of data in people's typical environments, RTDC is primarily used with self-reported data, such as medical symptoms and psychological states. Now, its guiding principles and supporting technologies also provide a framework for scientists to monitor physiological information such as heart rate, blood pressure, and skin conductance. This volume gives the most complete view yet of the state of RTDC science and its potential for use across the health and behavioural sciences.