Urbanization and monetization systems have contributed to the reclamation and exploitation of mangroves, which have had some significant effects on the livelihood of those who rely on it. Informal uses of mangroves have received very little attention because they do not contribute to national revenue, and the inextricably linked effects of urbanization and monetary systems on mangrove degradation is lacking. The purpose of this study is to examine the socio-economic impacts of development on mangrove ecosystems and those who depend on it in four coastal villages of Samoa. Fifty households' questionnaire-assisted interviews were conducted first, to provide the social, cultural and economic value of mangroves to the local inhabitants. Second, to identify activities that have changed mangrove ecosystems, and then, to examine how these activities have changed the local inhabitants' social, cultural, and economic relationships with their environment. Findings suggest that, in two cases, land reclamation has strictly and seriously degraded mangrove resources particularly in terms of marine food supplies. For two other cases, increased accessibility to town and the monetization of the rural economy are also factors involved in the decline in quantity and size of fish catch due to the increasing reliance on sales of mangrove food resource for cash. This study supports the position that modern developmental initiatives must be carefully monitored to ensure that they do not undermine the social and economic well-being of resident communities, particularly in areas such as Samoa where a large proportion of the population relies on land and marine resources for their survival.