Barrier-to-autointegration factor (BAF) is an abundant, highly conserved, small and essential protein that binds to dsDNA, chromatin, nuclear lamina proteins, histones and various transcription factors. It was discovered as a cellular component of retrovirus pre-integration complex that inhibits their autointegration in vitro. BAF is also required for many cellular functions, including the higher-order organization of chromatin and the transcription of specific genes. Recent findings suggest further roles for BAF, including nuclear envelope assembly, regulating specific developmental processes and regulating retrovirus infectivity. At least some of these roles are controlled by phosphorylation of the BAF N-terminus by the vaccinia-related kinase. Here, we give an overview of recent advances in the field of BAF with special emphasis on evolution, interacting partners and functions.