Scientific literacy is an essential competency that pre-service elementary school (SD) teachers must master in order to foster their future students’ scientific literacy, yet assessment instruments designed specifically for this population remain scarce. This study aimed to develop a scientific literacy-oriented assessment instrument for pre-service SD teachers and to establish its content validity. Using the 4D model, the define, design, and develop stages were carried out, while developmental testing and dissemination were planned as subsequent stages. The instrument integrates three scientific competencies adapted from the PISA framework explaining phenomena scientifically; designing and evaluating scientific inquiry and interpreting data and evidence; and using scientific information for evidence-based decision-making into seven elementary science topics: the respiratory, digestive, and circulatory systems, electricity, the water cycle, the solar system, and biotechnology. The resulting instrument consists of eight contextual stimuli and 20 items (6 multiple-choice and 14 open-ended items).Five Science Education lecturers evaluated the content, construction, and language of each item, and content validity was analyzed using Aiken’s V. All items obtained V values between 0.82 and 0.92 (overall mean = 0.86), placing them in the high validity category, with comparable means for the three competencies. The items with the lowest values were higher-order items requiring inquiry evaluation or decision-making, indicating where refinement should be prioritized. The instrument is therefore content-valid and ready for field testing to examine its reliability, difficulty, and discrimination with pre-service SD teachers.