Purpose: This study investigated the language and cognitive skills of preschool children with sex chromosome trisomies (SCTs) with and without a co-diagnosis of developmental language disorder (DLD), considering possible differences between SCT types (i.e., XXX, XXY, and XYY). Method: Fifty-five children with a prenatally diagnosed SCT (19 XXX, 25 XXY, and 11 XYY) aged 48-64 months were included in the study. The presence of a DLD diagnosis or other neurodevelopmental disorder was established by structured interviews, while cognitive and language skills were assessed using a test battery including the Wechsler Preschool and Primary Scale of Intelligence--Third Edition, Test for Reception of Grammar--Second Edition, and selected Batteria per la Valutazione del Linguaggio in Bambini dai 4 ai 12 anni ("Battery for Language Assessment in Children Aged 4 to 12 Years") subtests. Results: Of the 55 children, 44 (76.4%) had a diagnosis of DLD at this stage. Cognitive assessments showed no significant differences in Performance IQ, Verbal IQ, and Processing Speed Quotient in children with SCTs. However, children with SCTs and co-occurring DLD scored lower than those without DLD in the last two areas. Language assessment revealed notable impairments, particularly in speech sound accuracy and repetition tasks, with children with a co-occurrent diagnosis of SCT and DLD reporting greater impairments. No significant differences in the prevalence of DLD were observed between SCT types. Conclusions: These findings highlight the importance of early identification and intervention on co-occurrent neurodevelopmental disorders in the population of children with SCTs. Further research should explore language and learning trajectories in the population of children with DLD with and without a co-occurring genetic diagnosis to better differentiate developmental characteristics and allow for effective tailored interventions.