The vast majority of research on natural hazards in the Philippines and Viet Nam tends to focus on risk estimation and modelling rather than adaptive capacity, especially the case of salt water intrusion. This study aims to analyze the adaptive capacity of rice-farming households to the salt water intrusion which is considered as slow onset event. This research will be conducted to determine more comprehensively the multidimensional indicators of adaptive capacity of rural farming households to address saltwater intrusion in the two countries. The main objective of this study is to employ mixed method design to develop a measure-based index to account for adaptation processes and define household-level variables that will potentially explain adaptive capacity by means of a regression model. The results of the research will hopefully show that the developed index will capture the complexity of adaptation processes that will address a number of shortcomings of the previous studies. The result of the determinants of adaptive capacity will lead to the generation of a model specific to rural rice-farming households in the two countries and in the context of saltwater intrusion.