Accurate chromosome segregation in mitosis requires cohesion between sister centromeres mediated by heterochromatin. Although establishment of both silent heterochromatin and cohesion require passage through S phase, the mechanism was previously unknown. In our recent paper, we demonstrate that heterochromatin silencing and cohesion at the centromere rely on temporal activation of the conserved S phase protein kinase Hsk1-Dfp1. Hsk1-Dfp1 is needed for heterochromatin assembly downstream of Swi6 binding to chromatin; importantly, this activity is independent of the replication function of Hsk1-Dfp1. This defines a temporal connection between S phase, heterochromatin and cohesion that is independent of replication fork passage.