The primary purpose of this study was to test the hypothesis that an important intellectual acquisition during adolescence is the ability to generate arguments that involve reasoning to contradiction. Students in grades 3, 5, 7, 9, 11, and college were individually administered a four-card selection task that required them to, among other things, reason to a contradiction to falsify a hypothesis. Virtually none of the students spontaneously utilized this reasoning pattern on the initial task. Minimal verbal instruction in use of the reasoning pattern was then given followed by a logically analogous selection task. Performance on this task improved significantly with age from 12% success among third graders to 52% success among college students, providing some support for the hypothesis. Performance on an evaluation task showed similar rates of success; however, most students were able to correctly evaluate falsifying evidence when presented. This result suggested that, contrary to Piagetian theory, students from grade 3 upward comprehend the logic of falsification. It is argued that reasoning to a contradiction is a reasoning pattern of central importance in testing alternative scientific hypotheses and its use in students grades 3 through college could be enhanced through proper instruction and, if done, should increase students' ability to generate and evaluate competing hypotheses.