ABSTRACT Educational institutions have witnessed an explosive growth in the numbers of children, adolescents, and adults labeled as learning disabled (LD). The term LD is used increasingly by both educators and the general public. Recently, the term has also appeared in the foreign language literature. However, the LD concept has come under increasing criticism because of the problems of finding an acceptable definition and the concept's lack of scientific validity. In a recent article in this journal, Ann Mabbott describes as LD five adults, all of whom have achieved degrees of proficiency in a foreign language. In this response to Mabbott, the authors take issue with her diagnosis of the subjects as LD because she provides neither substantive standardized testing evidence of the subjects' intellectual ability and academic achievement nor corroboration of the subjects' self-reports of their native and foreign language learning problems. The importance of using objective criteria to diminish heterogeneity in research samples is examined in the context of Mabbott's case studies.