The paper presents the speech database “AD-Child.Ru” that contains speech materials of 4-16 year old children with atypical development. The choice of informants with certain diagnoses is due to speech disorders or lagging speech development as one of the leading symptoms of each of these diseases. At the present time the database includes 1.1 Tb of audio and video records collected from children (n = 278) and adults aged 20-46 years (n = 20) with mental retardation (with a mental age of 12 years). Audio recordings were carried out in a model situation and spontaneous interaction with adults. This database is designed to study the speech development in dysontogenesis. The paper reports two experiments on the speech material included in the database “AD-Child.Ru”: (i) recognition by listeners of the words meaning of preschool typically developing (TD) children, children with autism spectrum disorders (ASD), and Down syndrome (DS); (ii) determination by the listeners of the child state “typical development – disorder”. Our database can be the basis for scientific projects on the Russian language mastering in case of atypical development and can be used in the studies of automated child speech recognition system.