Findings from two studies investigating the effects of a socially interactive robot on the vocalization production of young children with disabilities are reported. The two studies included seven children with autism, two children with Down syndrome, and two children with attention deficit disorders. The Language ENvironment Analysis (LENA) software package was used to continuously record child vocalizations during both baseline and intervention phases of the studies. Results showed that child-robot interactions were differentially effective in increasing the children's vocalization production. Several reasons are offered for the fact that child-robot interactions did not have vocalization production effects for a number of the children. The following are appended: (1) Popchilla World Software Speech Used in Study 1; and (2) Professionally Recorded Sounds and Speech Used in Study 2