High quality childcare greatly improves outcomes in later life. Yet childcare access and usage are distributed unevenly, leading to amplified inequalities in later life outcomes. Parents from low-income households are 50% less likely to use formal childcare services than high-income households and use them when the child is older and less intensely. Research has shown that cost, location, and quality of childcare effects usage, yet policy solutions aimed at removing these barriers have not reduced inequalities in usage. Aim - In this project, sociological, economic, demographic and social policy perspectives are synthesized within a framework of ‘complex contagions’ to investigate how the use of formal childcare diffuses across low income populations, with the aim of identifying barriers to uptake in formal childcare. Approach - This project breaks through the state of the art to more clearly describe why some childcare strategies, that use formal childcare, don’t spread to low income households. With a complex contagion, people only adopt a new behaviour if they are repeatedly exposed to it from multiple, diverse actors in their network. Low income households have personal networks with long weak ties and high, multi-layer clustering, that make adopting new childcare strategies unlikely. This project therefore examines how the childcare strategies present in work, family and neighbourhood networks influences the childcare strategies of low income households. Innovation & Impact - The analysis will draw on unprecedented, linked administrative and survey data to study the diffusion of childcare strategies. Network data are used in combination with multichannel sequence analysis and other longitudinal methods to identify the role of networks in shaping childcare strategies. The project will completely reframe our understanding of not only childcare strategies, but also parallel areas of social policy and the wider study of behaviour diffusion in the social sciences.