The Kwai Noi Dam Construction is a Royal Development Project in Phitsanulok which has had important effects in the form of losses of land and residences of people living in the area. Studies related to loss of land, in past on emigrants and non-emigrants, and details of compensation have been rare in this and similar projects. This study tries to develop on integrated approach to knowledge in this area. A population survey was conducted within the selected area by distributing questionnaires to 220 subjects, from 14 villages, and in-depth interviewing of 18 subjects. All questions focused on the impacts of the Kwai Noi Dam construction. The sample included emigrants and non-emigrants. Three government officers who deal with land expropriation and compensation were also interviewed. It was found that most of the land the residents had used belonged to the government and locals had no title deed. Therefore, the process of land compensation, properties, and extra compensation depended on land utilization before dam construction. However, many problems arose from the process of expropriation and compensation; for instance, there were delay in communication, ambiguous information, competing and conflicting assertions of rights to land, delays in payment, investment problems, and dissatisfaction. There was a manifest change in economic situations of both emigrants and nonemigrants, especially in occupation; they also did not receive compensation in accordance with the land lost and this led to reduction in annual income. These changes were worse for the emigrants than for non-emigrants. However, most emigrants and non-emigrants stated definitely that housing and communications were better. For relationships with the family and community, there were few changes because most of the sample still resided in the same area. As a result, traditional relationships and lifestyles were maintained. Furthermore, the result of the study suggests that there are different impact levels and different adaptability levels for people with different livelihoods. The government should take this into account when considering such project.