In recent decades, sympathy toward Israel among Leftists in Europe and the United States has given way to hostility. Perceived in its early years as a vital experiment in socialist democracy, Israel is now typically viewed by radicals and even many progressives as a colonialist power. What explains this shift in opinion? Does it reflect larger changes in the politics of the Left or, rather, changes in Israel? Does hostility toward Israel and Zionism have ramifications beyond the Left itself? These questions framed a day-long symposium on April 19, 2012, at the University of Wisconsin–Madison. This symposium was sponsored by the Mosse/Weinstein Center for Jewish Studies, with additional support from the Harvey Goldberg Center.