Throughout time, the indigenous populations of Misiones province, as well as some other populations in Argentina, have been part of encounters and interactions with other societies, which had similar or different lifestyles. The autonomy and decision-making capacity of these populations have been broken by most of those encounters with “others”, thus partially or completely changing their lifestyle. Some of those changes are related to several subsistence activities characterized by great temporal depth – including hunting, fishing and gathering, as well as the sustainable slash-and-burn agriculture of forests. There were also changes on the aboriginal language, food, clothing, housing and knowledge based on their particular ways of perceiving and interacting with their natural and social environment. Health, religious and educational institutions have been greatly responsible for those changes through the implementation of sometimes contradictory policies that alternatively favored change or appealed to increase the value of ancient cultural rules. Nowadays, tourism, like other types of undertakings fostered by different organizations, focuses on the attractiveness of what is different, either in terms of landscapes or human populations. To some extent, these projects promote aboriginal participation and urge these “populations to maintain their ‘traditional’lifestyles, their ‘identity’ – which must be evident – and their ‘authentic’ spirit in order to gain the approval of clientele looking forward to contacting other cultures and lifestyles.” (Santana Talavera, 2002:1). In this sense, the ethnographic studies of subsistence activities carried out in the Mbya-Guaraní populations of the Cuña Pirú Valley allow us to consider several aspects of the impact of tourism on their current lifestyle.