Ontologies are ways of representing information that promote clarity, consistency, and coherence. They are used in science to facilitate search and inference and interoperability across data sets and academic disciplines. To maximise ontologies for use within the behavioural sciences three things need to be achieved: First, ontologies in a domain should be interoperable so that they can be used together. However, behavioural scientists do not currently have a method - or ‘workflow’ - for making ontologies interoperable. [The DEMO-INTER project][1] will develop and evaluate a method for achieving interoperability between ontologies. Second, ontologies should be used to make working with datasets easier (e.g., searchable) and interoperable so that they can be combined in a way that maintains coherence and thereby provides insights that would not have been possible for data sets used in isolation. [The DEMO-DATA project][2] will develop and apply a methodology for annotating datasets in behavioural and social sciences, using data sets used for modelling population trends in smoking and e-cigarette use as an example. Third, to advance theory development, evaluation and use, it is important to develop a consistent, coherent and comprehensive way of representing theory constructs. [The DEMO-THEORY project][3] will map constructs in theories of behaviour change on to ontology classes for the purposes of theory searching, comparison and integration. This work is part of [Behavioural research UK's][4] demonstration projects, involving researchers and partner organisations from across the Hub working together to demonstrate a variety of types of question and methodology. Demonstration project 3 is part of BR-UK's work package on data and technology. You can read more about BR-UK on our website. [1]: http://doi.org/10.17605/OSF.IO/5E7J9 [2]: https://doi.org/10.17605/OSF.IO/A63J4 [3]: http://doi.org/10.17605/OSF.IO/MUY9N [4]: https://www.ed.ac.uk/usher/behavioural-research-uk