Mitosis and meiosis are remarkable processes during which cells undergo profound changes in their structure and physiology. These events are orchestrated with a precision that is worthy of a classical symphony, with different activities being switched on and off at precise times and locations throughout the cell. One essential 'conductor' of this symphony is the chromosomal passenger complex (CPC), which comprises Aurora-B protein kinase, the inner centromere protein INCENP, survivin and borealin (also known as Dasra-B). Studies of the CPC are providing insights into its functions, which range from chromosome-microtubule interactions to sister chromatid cohesion to cytokinesis, and constitute one of the most dynamic areas of ongoing mitosis and meiosis research.