This paper proposes a consumption model where the key of the purchase decision is the agent opinion. This opinion is multidimensional because it is shaped by direct opinion which depends on the agent’s perception and by indirect opinion which depends on social interaction. This framework is applied to the purchase decision of ethical goods to study the evolution conditions to improve the sustainable consumption. So, for testing the diffusion of ethical opinion on the population, we have built an agent-based model named Level of Ethical Opinion (LEO). This model simulates the evolution of opinion when the agents discuss (strong interaction) and when they change their good perception following information modification (weak interaction). 10.1007/978-3-540-70556-7\₇