High Quality Content by WIKIPEDIA articles! The University of Wisconsin MadHatters (or UW MadHatters) is a collegiate a cappella group on the University of Wisconsin-Madison campus. Created in 1997, the UW MadHatters are the first established a cappella group on the UW-Madison campus. The MadHatters have grown significantly in popularity in the a cappella community, having released several albums and receiving several awards. The MadHatters are notable for being featured on two Best of Collegiate A Cappella (BOCA) compilation albums as well as hosting the International Championship of Collegiate A Cappella. The MadHatters currently have 15 vocalists and two vocal percussionists.