It has been established in the literature, that individuals with intellectual disabilities often experience difficulties in social adjustment (Matson & Fee, 1991; Mulick, Hanson, & Dura, 1991) and experience high rates of peer rejection (Merrel, Merz, Johnson, & Ring, 1992). Furthermore, studies reveal that people with intellectual disabilities live with few connections and have limited friendships (Pottie & Sumarah, 2004). Individuals with Williams syndrome, have a similar social profile where they report feeling isolated, have difficulty making friends and experience failure in their social relationships (Tager-Flusberg, 2004; John, Rowe, & Mervis, 2009). However, individuals with Williams syndrome vastly differ from most other people with intellectual disabilities, with respect to their strong propensity for social engagement (John et al., 2009) and their strengths in expressive language and vocabulary. Currently, there is no research that examines social adjustment in friendship patterns among individuals with intellectual disabilities and individuals with Williams syndrome.

The current study compared eight individuals with Williams syndrome to thirteen individuals with intellectual disabilities, across various quantitative and qualitative measures of friendship. A Two-Phase Sequential Explanatory Mixed Method design was used. In the first phase, quantitative measures were employed to make comparisons between the two groups. In the second phase, qualitative methods involving small focus groups were used to explore the phenomenon of friendship within each diagnostic group.

Overall, results from the quantitative phase of the study demonstrated that individuals with Williams syndrome expressed greater closeness with their friends and enjoyed the company of others more than did individuals with intellectual disabilities. However, it was necessary to interpret these differences with caution because of IQ and gender differences between the two groups. Results from the qualitative phase illuminated differentiated understandings of friendship for the two diagnostic groups. In particular, the individuals with Williams syndrome showed a heightened tendency to express empathy and emotional support and to take on the perspective of their friend.