© 2017 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To assess the effects of non-occupational interventions for reducing sedentary behaviour in adults under 60 years of age on sedentary time. Secondary objectives are: to describe other health effects, and adverse events or unintended consequences of the interventions; to determine whether specific components of interventions are associated with changes in sedentary behaviour; to examine if there are any differential effects of interventions based on health inequalities (e.g. age, sex, income, employment).