Evaluating the « power » of NGO websites interface design over forms and strengths of commitments: between ethic, esthesie and resistance.We assess the level of user commitment on NGO websites by defining:i. an analytical framework linking user interactions with mediating devices (interaction models),ii. semiotics metadata describing individual user behaviour evolutions (interaction styles).This method allows us to discuss strategies from the perspective of co-enunciative relationship change depending on user interactions.Considering user perception produces a new indicator of the level of public support for the ethical message of NGO. We highlight a change of perspective to evaluate digital strategies: from a performance assessment focused on donations to the requirement of a co-enunciative relationship conducive to commitment.We define differents ways of interacting with NGO websites according to the relation between interaction models and interaction styles. Therefore, the level of user commitment on NGO websites depends on these different interaction possibilities provided by webdesign and covering a wide range of involvements from ignorance to empowerment.