Purpose. Behaviour change techniques are fundamental to the development of any behaviour change intervention, but surprisingly little is known about their properties. Key questions include when, why, how, in which contexts, for which behaviours, in what combinations, compared with what, and for whom behaviour change techniques are typically effective. The aims of the present paper are to: (1) articulate the scope of the challenge in understanding the properties of behaviour change techniques, (2) propose means by which to tackle this problem, and (3) call scientists to action. Methods. Iterative consensus (O'Connor et al., 2020, Br. J. Psychol., e12468) was used to elicit and distil the judgements of experts on how best to tackle the problem of understanding the nature and operation of behaviour change techniques.Results. We propose a worldwide network of 'Centres for Understanding Behaviour Change' (CUBiC) simultaneously undertaking research to establish what are the single and combined properties of behaviour change techniques across multiple behaviours and populations. We additionally provide a first attempt to systematize an approach thatThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.