A study investigated the reason for the high performance of bilingual children on a syllogistic reasoning task. Thirty-nine Puerto Rican Spanish-English bilingual children in grades 3 through 6 were asked to solve problems in both languages. Response times were recorded, and the subjects were asked to justify their answers to assess to what extent reasoning led to task success. Response times were found to be longer if the justification given reflected reasoning, but it was also found that students needed more time to give an answer in their stronger language (Spanish) than in their weaker one (English). In addition, solution accuracy and solution strategy did not interact and the strategies used to solve syllogisms were manifested differently at different grade levels. In the lower grades, the justification given seemed to reflect whether or not the student understood the purpose of the task, and in higher grades, the justification appeared to show whether the student succeeded in his reasoning effort or used a default strategy to solve the problem. Performance above the chance level is attributable to the characteristics of the syllogism rather than to what the subjects did with them, suggesting that strategy rather than success is a better source of information about children's performance. (MSE)