Most microbes live in spatially structured communities such as biofilms in which they interact with their neighbors through the local exchange of diffusible molecules. To understand and manipulate the functions performed by these communities, it is essential to uncover how community-level properties, such as the community composition, arrangement, and growth rate, arise from these local interactions. I will show how we can combine single-cell microscopy with mathematical modelling to develop a quantitative framework to predict community-level properties from the molecular mechanisms underlying the cell-cell interactions. Our framework thus allows us scale between molecular and community level dynamics and lays the groundwork for developing a quantitative understanding of how microbial communities function.