The Acai, a fruit of the Acai tree (Euterpe oleracea Mart.), is one of the main foods consumed by the riverside communities in the Brazilian Amazon. In addition, it has become the main source of income of these small producers as its consumption has widely expanded since the 1990s due to the recognition of its properties as an energetic and functional food. In order to analyze the production system and the socioeconomic changes that occurred in rural communities whose economical support is from the management of the Acai tree, a case study was carried out in two communities on the island of Mamangal, in the municipality of Igarapé-Miri, in the state of Pará, Brazilian Amazon. Fifty-two semistructured questionnaires were applied to the Acai farming families in these communities located in the municipality in the largest Brazilian producer of this fruit. The main transformations observed in the assessed communities, especially since the last decade, were influenced by the access to electric energy and the expansion of income from the Acai that made possible the expansion of the acquisition of durable consumer goods that even contributed to diversifying the diet of those farmers. Some of the difficulties faced by Acai production are the lack of technical assistance and rural extension services as well in addition to the strong dependence of the communities on the income generated by the Acai.