Despite the possibility of poor teacher performance causing damage to pupils and to a school's reputation, the subject has rarely been studied. This article examines, within the Israeli context, who the poor performing (referred as "challenging") teachers are. Based on interviews with 40 elementary school principals, over 7 percent of staff members were defined as "challenging"; mostly these were veteran teachers who manifested either insensitive attitudes towards pupils or had low motivation. The larger proportion of these teachers taught in deprived schools with inexperienced principals.