William & Mary is extremely safe. Theft is virtually nonexistent, particularly among the student community, considering that every student is required to take an honor pledge asserting not to lie, cheat, or steal (a tradition instituted in Thomas Jefferson's time). Most students take this very seriously, and therefore, instances of theft in student centers (like the library, for instance) usually never occur. People are also keen on leaving their doors unlocked for this very reason, which, though it is not condoned, doesn't usually result in theft or assault of any kind. The community also has a very safe atmosphere, considering most of the people you'll encounter during the day include other students, elderly people, or families touring the colonial area. There have been instances wherein a suspicious individual is spotted lingering around residence areas at night, but all occurrences are promptly taken care of by the William & Mary or Williamsburg police departments, which are very quick to respond to any sort of criminal case (which in itself is extremely rare).
As far as violence or sexual assault goes, instances of such are reported as rarely as a few times a year. William & Mary staff and faculty are quick to send out a message reporting such incidents and any information about culprits in any case, and also to provide students with means of coping with or reporting such instances of assaults. There are various help hotlines for those who have experienced assault, as well, though the occurrence of assault on campus is very rare.