India faces a major public health issue as it has the highest rate of open defecation in the world. Open defecation is associated with significant negative effects such as diarrhea, parasitic worm infections and stunting. Over the past few decades, the Indian government launched multiple campaigns to tackle this issue. Unfortunately, the campaigns have achieved limited success in changing the population’s open defecation behaviour. In 2014, the Modi government launched the Swachh Bharat Abhiyan (Clean India Mission) with the aim of eliminating open defecation in five years. As of 2018, however, 44% of Indians still defecate in the open. As a result, it is increasingly important to understand the social and behavioral drivers that motivate open defecation behaviour. The aim of this paper is to study the effects of social networks and social interactions on an individual’s open defecation behaviour. The survey data used in this paper is from a three-year long research project conducted by Penn Social Norms Group (Penn SoNG) in association with the Bill and Melinda Gates Foundation. A total of 3370 respondents were surveyed from two Indian states – Bihar and Tamil Nadu. The results of the regression analysis show that visiting religious sites as well as interacting with the village headman increases the likelihood of abstaining from open defecation by approximately 70%. Secondary analyses showed that television and billboard advertisements were particularly effective in reducing open defecation. Finally, this paper also attempts to identify potential trendsetters who can be leveraged in future behaviour change interventions. Hence, the results of the analysis suggest that by harnessing the power of social networks we can significantly influence people’s behaviour and ultimately alleviate the negative outcomes of open defecation in India.