The relationships between adolescents' reading comprehension and their metacognitive knowledge and self-system beliefs were studied in three groups of subjects: French nationals, Caucasian Americans, and African Americans. Subjects were tested on measures of reading comprehension, metacognitive knowledge about reading processes, attributional beliefs, and academic self-concept. Correlation and regression analyses indicated cultural differences in the predictors of reading comprehension among the three groups. For French and Caucasian Americans, reading comprehension scores were related to metacognitive knowledge, academic self-concept, and attributions of success to ability. However, metacognition and motivational beliefs were mostly unrelated to comprehension performance for African Americans. Results are discussed in terms of verification of a model of motivational influences on performance, of cultural and ethnic group differences in beliefs, and the implications for generalizability of research results.