Giving people agency within a health behaviour change intervention may be both desirable and effective. Smartphone apps make this approach possible for a large part of the population. If this works, however, it is also vital to understand how and why an app is effective. This blog by Larisa Dina (UCL) describes the process evaluation of a recent trial run by UCL researchers evaluating how engagement with an alcohol reduction app, Drink Less, and participants behavioural characteristics underpin its effectiveness. … More Keeping track: Finding the “how it works” for an app on cutting down drinking