This chapter describes the types of data that empirical community ecologists typically collect, and how these can be incorporated in the Hierarchical Modelling of Species Communities (HMSC) framework as input. While community ecologists apply theoretical, experimental and observational approaches to studying the processes that structure ecological communities, this chapter (and the entire book) focuses mainly on empirical research based on non-manipulative observational data. Understanding the basic features of the data and how they have been collected will be essential for appropriately setting up the HMSC model and interpreting the results. The chapter describes each type of input HMSC data, namely the community data (i.e. the occurrences or abundances of the species), environmental data, data describing the spatio-temporal context, species trait data and phylogenetic data. Finally, the chapter discusses how to best organise the data, as well as how to solve problems arising from missing data.