The relationship of self-concept and locus of control with the achievement of deaf adolescents was examined. The Rotter Internal-External Locus of Control Scale and the Piers-Harris Children's Self-Concept Scale, along with modifications of each to compensate for problematic syntax and vocabulary, were administered to 90 deaf adolescents from four residential schools. The achievement data came from standardized test scores in the students' records. Generally, parent hearing status and self-concept were the most important predictors of achievement. An increase in the prediction of achievement for six of nine subtests resulted when the modified forms of the scales were used in place of the original forms. This increase was due particularly to the locus of control variable.