As C. Kocian so accurately notes, it really depends on where you are in Belize. In some villages in northern and western Belize, Spanish is by far the dominant language, and often you will run across folks who speak no English at all, or hardly any. In Belize City and other Creole areas, it's almost all English and Creole (or Beliz Kriol as some write it). In places like San Pedro and Corozal which was originally settled by people from Mexico, most local people are fluent in both Spanish and English but often speak Spanish at home. In Maya areas it's Yucatec or Ketchi depending on where you are. In Garifuna towns/villages it's English, Creole and Garifuna. Some Mennonites speak a German dialect among themselves. Creole used to be the "lingua franca" among all groups in Belize including grigos who had lived in Belize a while, and still is to some extent, but with the emergence of Mestizos as the major ethnic group in Belize -- soon to be twice as numerous as Creoles -- Spanish is rapidly becoming the dominant language.
--Lan Sluder www.belizefirst.com