This study aims to further explore the implications of autism spectrum disorder (ASD) symptoms for children who do not meet full diagnostic criteria. More specific characterization of how challenges present relative to traits of ASD such as social responsiveness is vital to developing an understanding of what competency and mental health difficulties these impairments are related to, and if they persist over time. Assessments of autistic traits, clinical symptomotology, and competency were used to quantify the relation of these domains cross-sectionally and across time. Social Responsiveness Scale (SRS) scores significantly contributed to a teacher-report Happy scale from the Teacher’s Report Form and a parent-report Social scale from the Child Behavior Checklist. No significant longitudinal models emerged. Splitting the SRS scores into three severity classes revealed that impaired social responsiveness is significantly related to competency, unlike average or below average deficits. Implications of subthreshold ASD traits on competency outcomes are discussed.