An adaptive governance system strives to enhance th e capacity of institutions to better coordinate between them. As such, the main objective of an ada ptive governance system would be to put learning by experience processes in place, and thus to improve the adaptive capacity of the concerned system. The contribution of this paper is twofold: (1) to establish an assessment framework of the adaptive capacity of a system in t he field of natural disasters and (2) to explore the governance system of Mt. Merapi, Indonesia. Firstly, this paper establishes an assessment frame work for the adaptive capacity of a system in the field of natural disasters. This assessment framewo rk contains six key parameters as follows: (1) context description, (2) institutions, (3) infrastr uctures, (4) economic and financial resources, (5) technology, and (6) information and skills. Secondly, using a field survey, which was conducted after the 2010 volcanic eruption and rain- triggered lahars on Mt. Merapi, Indonesia, we under line a number of barriers, such as lack of appropriate infrastructures, complex interactions a cross institutions, dependence on funds from external parties, and rudimentary quantitative docu mentation on both human and material loss, that weaken the adaptive capacity of the rescue system. More efforts are therefore needed in order to improve the adaptive capacity and, thus, the adapti ve governance at Mt. Merapi system. This study constitutes a significant step toward en hancing our understanding of the adaptive governance approach in the context of natural disas ters in developing countries.