Nature Astronomy, Published online: 13 August 2026; doi:10.1038/s41550-026-02941-3 Accretion and relativistic jet formation in black holes occur across a wide range of their masses, revealing qualitative and quantitative similarities that connect the entire population of black holes. In March 2026, researchers from all areas across the black hole mass spectrum met in Oxford to educate, explore and forge new research directions.