The Social Responsiveness Scale (SRS; Constantino and Gruber in Social Responsiveness Scale (SRS). Western Psychological Services, Los Angeles, 2005) is a commonly used screening tool for identifying children with possible autism spectrum disorder (ASD). This study investigated the relationship between SRS scores and eventual diagnostic outcome for children referred to a tertiary level, autism specific assessment service. Forty eight children (mean age = 8.10; 92% male) underwent a comprehensive ASD assessment. Parent and teacher SRS scores were subsequently compared with diagnostic outcome. Sensitivity was high (91% for parent report; 84% for teacher report), however specificity was much lower (8% for parent report; 41% for teacher report). Results demonstrate a need for caution when interpreting SRS results based on current cut-off scores, particularly in children with previously identified social developmental problems.