The study assessed the use of Blissymbols in the spoken and signed language development of 10 school-aged (mean age 11.5 years) children with developmental dysphasia of whom four also were mildly retarded. The students' expressive abilities in signed and spoken words were initially assessed before the Bliss teaching began, and then again after 1 and 2 years. The total number of expressed symbols in all three communication systems showed a positive trend over the study period. The most statistically significant change was in spoken expression of adjectives in favor of communication by Blissymbols. It was also found that certain concepts which originally had been spoken or signed were later expressed only in sign or by using Blissymbols. Results are discussed in terms of implications for research, teaching, and communicative interactions. Includes 32 references. (DB)