The UNSW Business School research network on Behavioural Insights for Business and Policy held an invitation-only roundtable on the afternoon of November 8, 2016. This explored how three core themes – Big Data, Behavioural Economics, and Big Theory – can be harnessed in order to reinforce their value added to business (profit and not-for-profit) and government entities. Big Data has the advantages of large sample sizes and associated statistical power, unobtrusive data collection, and objective measures, but tends to be backward-looking by its very nature. Behavioural Economics offers a nuanced understanding of how real people make decisions, and how this decision-making can be facilitated by defaults and nudges. Effective defaults and nudges, in turn, are informed by Big Theory –insights of behavioural social science that have shown to be robust across a variety of contexts. Participants had the opportunity to benchmark their use of behavioural economics with the latest in academic research and industry best practice, and to engage in constructive discussion with their fellow participants and the roundtable speakers and facilitators. Three members of the Behavioural Insights research network sketched the key ideas related to the Big Data, Behavioural Economics and Big Theory to provide background and to facilitate roundtable discussions of how behavioural insights could be used in order to obtain an evidence-based competitive advantage within an organisation, in relations with customers and suppliers, and regarding partners and other stakeholders.