Extension Advisory Service (EAS) providers, who are mostly extension staff of agriculture 31 departments in developing countries, can serve as key agents of change in the development of 32 nutrition-sensitive agriculture (NSA). However, the conventional knowledge domains and 33 mandates of EAS staff are generally confined to production practices involving the use of 34 inputs and new technologies to improve crop productivity. The potential role of EAS staff in 35 promoting NSA may be hampered by their lack of knowledge of what NSA involves. We 36 develop a standardised and validated instrument to assess the knowledge of EAS staff on 37 different dimensions of NSA and their training needs. A survey of EAS staff in India using the 38 instrument highlights the significant knowledge gaps of EAS staff on NSA. We also find that 39 there are significant differences in the knowledge levels of EAS staff with and without NSA 40 training. We show that NSA training based on a systematic assessment of knowledge gaps can 41 strengthen the capacity of EAS staff to bring about the nutritionally sensitive transformation of 42 agriculture in developing country contexts.