Although there have been developments in understanding loneliness in children and adolescents, there is still very limited understanding of the construct in children and adolescents diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). The Perth A-Loneness scale (PALs), which comprises 24 items measuring four dimensions of loneliness in young people, was administered to 84 children and adolescents who had been clinically diagnosed as meeting criteria for ADHD. Eighty four individually age and gender matched non ADHD Community Comparisons with no diagnosed neurological deficits also completed the PALs. Competing measurement models were evaluated using confirmatory factor analysis and a first-order model represented by four correlated factors (Friendship Loneliness, Isolation, Negative Attitude to Solitude, and Positive Attitude to Solitude) was superior: CMIN/DF ratio (1.644), CFI (0.90), and RMSEA = 0.056 (90 % CI: 0.05, 0.07). A multivariate analysis of variance revealed no significant multivariate interactions or main effects of Group (ADHD/Non ADHD) or Sex (Male/Female). Overlap of 90 to 98 % between the ADHD and non ADHD samples in their 95 % Confidence Intervals for each of the four loneliness scores along with very small Effect Sizes further strengthened the finding of a non-significant main effect.