For a living cell to divide successfully, each daughter cell must inherit the correct genetic material. In eukaryotes, segregation of duplicated chromosomes is performed by the mitotic spindle, a cellular machine composed of microtubules and their associated proteins. Spindles are built from microtubules, which have biochemically distinct plus and minus ends. Specialized sites on the chromosomes called kinetochores attach to spindle microtubules, and these kinetochore-microtubule attachments are necessary for proper chromosome segregation. Problems in kinetochore-microtubule attachment and chromosome segregation can lead to aneuploidy, which is associated with birth defects and cancer progression. Kinetochore capture by spindle microtubules and the subsequent chromosome movements occur via highly dynamic microtubules that maintain kinetochore attachment during significant microtubule turnover. We are working to understanding how the mitotic spindle organizes and moves chromosomes. Recent projects have focused on the contributions of kinesin-8 motor proteins to chromosome movements, and kinetochore capture in early mitosis.