Background and aims: Research on typically developing (TD) populations has shown that the home learning environment plays a significant role in cognitive development and learning, but very little is known about the home learning environment of children with Down syndrome (DS) or children with Williams syndrome (WS). The present study examined and compared, for the first time, the home learning environment of children diagnosed with DS and children diagnosed with WS to investigate whether different cognitive profiles were reflected in their home literacy and number experiences. Methods and procedures: Quantitative and qualitative data were collected through a web-based survey from 58 parents and one foster parent of primary school children with DS (n = 35) and WS (n = 24) mostly based in the UK. The survey targeted the children’s general level of functioning and academic skills; type, format, and frequency of home learning activities; parents’ expectations for their child’s academic outcomes; parents’ attitudes towards literacy and mathematics; children’s interest towards mathematics; and the use of technology to support home learning activities. Outcomes and results: Our results showed that, overall, the home learning environment of children with DS and children with WS were similar but changed based on the child’s cognitive profile. Comparative analyses showed that parents of children with DS engaged more often in activities supporting counting than parents of children with WS, despite both groups reporting difficulties with this skill. Moreover, our results indicated that literacy-based activities occurred more often than mathematics-based activities and that the home numeracy environment was characterized by activities supporting different mathematical skills such as counting, arithmetic, and numeracy. Parents in both groups engaged with their child in both formal and informal literacy and mathematics-based activities, but informal activities occurred more often when supporting counting and number recognition skills. Conclusions and implications: The current study provides evidence that the home learning environment of children with DS and children with WS include different literacy- and mathematics-based activities and that the home learning environment changes on the basis of the child’s strengths and weaknesses. The findings are discussed in relation to previous studies and the impact on parental interventions.