Kammala wannan jumla: Maguire ya kasance tauraron dan wasa ne ga Makarantar Delbarton, yana taimakawa tawagarsa ta lashe Kofin Mennen hudu a jere kuma ta lashe rabon gasar zakarun jihar a matsayin matashi. Bayan kammala karatunsa a shekarar 1990, Montreal Canadiens ne suka zaɓe shi a gasar zakarun Turai ta 1990.
NHL Draft sannan ya fara halartar Jami'ar Harvard a cikin kaka. Maguire ya kasance dan wasa mai tsaron gida a kwaleji, yana wasa da abokan hamayya masu tsauri, amma har yanzu yana iya taimaka wa Crimson ya gama saman ECAC Hockey standings shekaru uku a jere. A lokacinsa na ƙarshe, wasan Maguire na kai hari ya rayu kuma ya ninka aikinsa na baya fiye da sau biyu. An kira shi All-American kuma ya tura Harvard zuwa gasar zakarun ECAC da kuma bayyanar a cikin Frozen Four.