After receiving knowledge regarding some topic, people usually overestimate their prior topic knowledge. Two experiments investigated whether people would claim less prior knowledge if they worked to earn their present knowledge. In Study 1, students finishing a psychology course claimed less precourse psychology knowledge if they reported devoting more effort toward the course. In Study 2, the knew-it-all-along effect was stronger for participants who were simply given the answers to questions than for participants who studied for 20 minutes to learn the answers. Both cognitive and motivational factors can account for the observed effects of effort investment on retrospective knowledge judgments.