A systematic review evaluated the validity and reliability of communication questionnaires used for individuals with intellectual disabilities. Conducting the review followed PRISMA 2020 guidelines and COSMIN definitions, searching five databases for studies published between 2000 and 2024. The inclusion criteria focused on questionnaires that assess communication and report on their validity or reliability. Six questionnaires from five studies and three manuals were included. The findings revealed more frequent reporting of validity evidence than reliability, but both were inconsistently documented. None of the questionnaires provided a comprehensive assessment of validity or reliability, with content validity often limited due to insufficient stakeholder involvement. The review concluded that while the current questionnaires show potential, they need further validation. Future research should emphasize stakeholder engagement, as well as enhancing content and structural validity to develop reliable communication assessments for this population.