We investigated the effects of instructions to "stay on task" on preschoolers' attention and cognitive performance in the face of either incomprehensible or comprehensible distraction. Three- and 4-year-olds completed problem-solving tasks while a distracting event played continuously in the background under conditions of (a) no instruction, (b) moderate instruction, or (c) frequent instruction to "stay on task." Under conditions where an incomprehensible distractor was present, "any" amount of instruction reduced looking to the distracting event. Under conditions where a comprehensible distractor was present, however, frequent instruction was the most effective in increasing looking to the task and decreasing looking to the distracting event. (Contains 2 tables and 1 footnote.)