This study was designed to compare the effects of speech and speech-plus-sign stimulation during comprehension treatment on the oral language learning and generalization of action + object relational meanings. Ten home-reared Down's syndrome children in Early Stage I received concurrent comprehension treatment in Speech and Speech-Sign conditions using a miniature linguistic system. Upon attainment of criterion level performance in both conditions, generalization tasks were administered to measure the effects of the comprehension treatment on the comprehension and the production of treated and untreated action + object combinations. The results obtained from this study indicated that the two treatment conditions did not differ significantly for either learning or generalization. The data did, however, indicate that individual patterns of acquisition were evident among the children. Caution is advised concerning the automatic adoption or rejection of manual sign as part of oral language intervention programs.