As in other developed countries, Portugal’s tourism sector is still too dependent on natural resources consumption, being one of the biggest contributors to the country’s economy but also to its big ecological footprint. Unfortunately, the Environmental Education in this sector is too restricted to a few issues (e.g. water; energy) and mainly corporate, either excluding tourists or being ineffective in this regard. Much more can be done on this sector regarding apartments, hotels, leisure centres, restaurants, shopping areas, private transportation networks, etc. improving competitiveness against other non-sustainable projects. Following this belief, a set of studies have been developed with the support of WWF, BioRegional and a team of consultants, in order to design the first certified sustainable tourism project in Portugal. This sustainable tourism project adopted a sustainability viewpoint by considering economic, environmental and social issues together, included in the One Planet Living Principles (ruled at the time). All these aims were taken into consideration in the project’s design phase through two complementary actions: 1) structural design and 2) behavioral design. In this presentation we will focus mainly on the latter. The behavioral design consisted of a set of intervention strategies aimed to the change, promote and maintain sustainable consumption practices, put forward in the following phases (Palma-Oliveira & Gaspar de Carvalho, 2004): 1) Psychosocial diagnostic; 2) Behavioral targets definition; 3) attitudinal and behavioral change strategies development; 4) project evaluation and monitoring definition. These allowed among other things, the development of a portuguese consumer profile, characterizing their behaviors in terms of type, frequency and characteristics for example. In addition, a prediction was made about the types of users expected at the tourist site and the contexts and places they would be in. This gave rise to behavioral targets fitted to the different people and site characteristics, followed by associated behavioral change, promotion and maintenance strategies. Also, an assessment phase was defined, to assess the feasibility and practicability of the measures, and also the project’s success and impact (Gaspar de Carvalho & Palma-Oliveira, 2007). Similar projects in Portugal followed this one, which are nowadays being adapted to the sites specificities, in order to reduce Portugal's tourism ecological footprint.