Child Behavior Checklist (CBCL) 1.5–5 CBCL 1.5–5 year [5 ] subscale scores are derived for the following syndromes: Emotionally Reactive, Anxious/Depressed, Somatic Complaints, Withdrawn, Sleep Problems, Attention Problems, and Aggressive Behaviour, and these are further summed to provide scores for Internalizing and Externalizing problems.   The CBCL 1.5–5 was assessed by one paper of good methodological quality [72] with a sample of children with ASD. This paper provided evidence of good internal consistency for total problems (Cronbach’s alpha = 0.93) and both the externalizing behaviour domain (Cronbach’s alpha = 0.90) and aggressive behaviour sub-scale (Cronbach’s alpha = 0.80). No evidence was found concerning reliability. Structural validity was also good with an acceptable model fit for a one-factor model for aggressive behaviour ( RMSEA<0.06, Comparative Fit Index (CFI)>0.95) i ndicating that there was a single latent factor underlying this sub-scale.