Purpose: Autistic boys and boys with co-occurring fragile X syndrome and autism spectrum disorder (FXS + ASD) demonstrate similar pragmatic language difficulties. The Pragmatic Rating Scale--School Age (PRS-SA) captures ecologically valid metrics of pragmatic language impairments in these populations. It is traditionally scored based on the Autism Diagnostic Observation Schedule (ADOS), which may limit the use of the PRS-SA more broadly in research and clinical contexts. Method: This study evaluated the feasibility of the PRS-SA based on a shorter, semistructured conversational context compared to the ADOS in school-age autistic boys (n = 16) and boys with FXS + ASD (n = 16), matched on ASD traits. Differences across ADOS and conversational contexts and associations with ASD-related social difficulties were evaluated. Results: Findings revealed differences in PRS-SA scores between ADOS and conversational contexts, but only for the FXS + ASD group. Limited associations were observed between PRS-SA scores and ASD traits. Conclusions: Results from this study indicate the feasibility of using the PRS-SA in a shorter conversational context than the ADOS to assess pragmatic language among autistic boys. For boys with FXS + ASD, contextual differences warrant careful consideration in future work.