Dissecting Chromosome Segregation During cell division, the centromere regions of chromosomes assemble multiprotein organelles called kinetochores that form attachments to spindle microtubules. Working in Caenorhabditis elegans , Cheerambathur et al. (p. 1239 , published online 14 November) describe a mechanism controlling the formation of kinetochore-spindle microtubule attachments that is essential for accurate chromosome segregation. The findings suggest the existence of crosstalk between the two major protein complexes involved in forming spindle microtubule attachments: the kinetochore dynein module, which initially captures spindle microtubules, and the Ndc80 complex, which ultimately forms the dynamic end-coupled attachments that segregate chromosomes.