We examined sibling relationships for children and adolescents with intellectual disability and assessed implications for their social functioning. Targets (total N = 212) had either intellectual disability, a chronic illness/physical disability, or no disability. Nontarget siblings reported on relationship quality, sibling interactions were observed, and teachers reported on social adjustment. Group comparisons highlighted the asymmetrical hierarchy and low conflict unique to siblings and targets with intellectual disability. Sibling relationships characterized by high warmth/closeness, positive affect, and few negative behaviors were predictive of fewer behavior problems for the targets at school. Both high warmth/ closeness and high conflict predicted greater social competence for the targets with intellectual disability, though warmth, conflict, and sibling management had different implications depending on the sibling's gender.

Differential diagnosis of young children with suspected autism spectrum disorder (ASD) is challenging, and clinician uncertainty about a child's diagnosis may contribute to misdiagnosis and subsequent delays in access to early treatment. The current study was designed to replicate and expand a recent report in this

Cross-sectional (N = 106) and longitudinal (N = 35) samples of siblings (ages 11-38) reported on closeness and conflict in their relationships with sisters and brothers with intellectual disability. For closeness, confirmatory factor analysis (CFA) distinguished feelings of emotional closeness from reciprocal sharing behaviors for these siblings. Age effects and changes over time indicated increasing emotional closeness and a general reduction in conflict from adolescence to young adulthood, with stable reciprocal sharing. Cross-sectionally, closeness was greater when siblings were involved in caregiving, and conflict was less when siblings no longer co-resided. Sibling constellation features (sex, birth order, age spacing) had limited effects at this developmental period. Findings support a combination of life-span developmental change and enduring attachment in these sibling relationships.

Children with ASD missed by screeners had higher scores on developmental testing and lower scores on the ADOS-2; however, children still performed below average on developmental tests. Our findings suggest that a combined screening approach was most effective for identifying children with ASD from a sample group referred for an ASD evaluation.