Estimates of the number of persons with speech disorders vary according to identification criteria and survey methods used. Figures also differ as a function of intelligence, emotional maturity, and physical status. A most valuable collection of incidence data was presented by Milisen (54), who found that approximately 12-15 percent of elementary and 4-5 percent of older school children had serious speech defects, mostly nonorganic articulatory errors. Stuttering and voice disorders each accounted for approximately 1 percent in addition. McCarthy (46) and Milisen (54) reported that boys tend to have more speech and language deficiencies than girls, the ratio varying from insignificant fractional differences in articulatory defects to 10:1 for stuttering. Templin (98) noted, however, that such ratios are not as great as earlier studies indicated.