The purpose of the present research was to comprehensively assess the language abilities of Russian primary-school-aged children with Autism Spectrum Disorder (ASD), varying in non-verbal IQ, at all linguistic levels (phonology, lexicon, morphosyntax, and discourse) in production and comprehension. Yet, the influence of such non-language factors as children's age, the severity of autistic traits, and non-verbal IQ on language functioning was studied. Our results indicate a high variability of language skills in children with ASD (from normal to impaired) which is in line with the previous studies. Interestingly, the number of children with normal language abilities was related to the linguistic levels: according to more complex morphosyntax and discourse tests, fewer children with ASD were within the normal range unlike the results in simpler phonological and lexical tests. Importantly, we found that language abilities were best predicted by non-verbal IQ but were independent from age and the severity of autistic traits. The findings support the claim that formal language assessment of children with ASD needs to include all linguistic levels, from phonology to discourse, for helping speech-language therapists to choose an appropriate therapy target.