The main objective of this study is to investigate and provide further empirical evidence of the complex relationship between poverty and social and economic vulnerability in a case study of urban Thailand. From our pre-survey, these house characters are expected to affect flood decisively. The case study is carried out in Bangkok and Pathumthani province. In both case study areas, there are some communities joining “The Baan Mankong Collective Housing Program (BM Program)” which as one pillar to improve the house for low-income people. In the field survey, in-depth interview and face-to-face questionnaire survey at the household level were conducted. As the results, average “situation of the flood”, “damage level” in Pathumthani province found higher than in Bangkok that notifies damage on a house in Pathumthani province is more severe than in Bangkok. As expected, risk exposures have the positive correlation with flood damage. There are several indicators of “adaptation to risk", and especially house characters have the significant correlation with risk exposure and flood damage. Moreover, there is no significant relationship between poverty and adaptation to risk. By the way, poor communities have social capital; they can join the BM program and receive support to improve their house. This study reveals that the most vulnerable group is poor communities that locate in the more flood-prone area and look rather a drawback in social capital. Originally a low-income community is vulnerable and can not join the program that supports to enhance its adaptation to risk. To mitigate poor people's vulnerability to flood, enhancing their social capital is through indirect but essential way.