The goal of this research is to study the speech strategies of adults' interactions with 4-7-year-old children. The participants are "mother-child" dyads with typically developing (TD, n = 40) children, children with autism spectrum disorders (ASDs, n = 20), Down syndrome (DS, n = 10), and "experimenter-orphan" pairs (n = 20). Spectrographic, linguistic, phonetic, and perceptual analyses (n = 465 listeners) of children's speech and mothers' speech (MS) are executed. The analysis of audio records by listeners (n = 10) and the elements of nonverbal behavior on the basis of video records by experts (n = 5) are made. Differences in the speech behavior strategies of mothers during interactions with TD children, children with ASD, and children with DS are revealed. The different strategies of "mother-child" interactions depending on the severity of the child's developmental disorders and the child's age are described. The same features of MS addressed to TD children with low levels of speech formation are used in MS directed to children with atypical development. The acoustic features of MS correlated with a high level of TD child speech development do not lead to a similar correlation in dyads with ASD and DS children. The perceptual and phonetic features of the speech of children of all groups are described.