<![CDATA[Children with Autism Spectrum Disorder (ASD) experience significant barriers in receptive and expressive language skills that impact on limited functional communication in daily life. These barriers often give rise to problematic behavior as an alternative form of communication when children are unable to convey needs verbally. This study aims to analyze the effect of the Picture Exchange Communication System (PECS) on the receptive and expressive language skills of five children with ASD in Special Needs Schools (SLB) using a Single Subject Research (SSR) A–B–A pattern design, consisting of baseline-1 (4 sessions), intervention (12 sessions), and baseline-2 (4 sessions) for eight weeks. The research instrument was a language ability observation sheet validated through expert judgment, and the intervention media was 90 PECS picture cards grouped into nine functional vocabulary categories. Data were analyzed using SSR visual analysis (trend, level, stability, and overlapping data) equipped with effect sizes of Percentage of Non-overlapping Data (PND) and Tau-U. The results of the study showed that four out of five subjects (80%) experienced consistent and sustained language improvement in the baseline-2 phase, with an average score increase ranging from 34.25 to 53.75 points in three subjects whose data had been fully analyzed quantitatively, while one subject had not shown a significant response due to the lack of joint attention skills as a prerequisite for communication. This finding confirms that the effectiveness of PECS is individual and highly dependent on the readiness of the child's communication prerequisites, while strengthening PECS's position as an evidence-based practice in language learning for children with ASD in special education settings in Indonesia.]]>
