This study examined middle school students' reading motivation and its relations to their performance on a standardized test (ISTEP+) in reading. Participants included 388 sixth- and eighth-grade students from two public middle schools. There were 229 females and 159 males. Participants responded to the Reading Motivation Questionnaire after they had completed the ISTEP+ test. Results showed that students who had high self-efficacy in their reading, read challenging material, and read for aesthetic enjoyment did better on the ISTEP+ test. Students who read mostly for social reasons did poorly on the ISTEP+ test. Grade, gender, and racial differences were found. (Contains 8 tables.)