The 2009 IIHF World U20 Championship Division I took place between December 14 and December 21, 2008 in Herisau, Switzerland and Aalborg, Denmark. Teams were divided into two groups, with Group A playing in Switzerland, and Group B playing in Denmark. The winner of each group is promoted to the Top Division for the 2010 IIHF World U20 Championship, while the last place teams in each group are relegated to Division II for the 2010 IIHF World U20 Championship.