We study the mechanisms of meiotic and mitotic cell cycle regulation leading up to chromosome segregation and gamete formation. Errors in meiosis can have devastating consequences, causing miscarriage, infertility and trisomy conditions. Errors in mitotic cell cycle regulation can result in cancer. We seek to understand how errors in meiosis and mitosis occur by studying how cells progress through a series of ordered events, how chromosomes attach to spindle microtubules, and how this attachment is monitored by the spindle checkpoint. We use both budding yeast and mouse oocytes for our studies.