This dissertation deals with persuasive communication in the context of social marketing, which is a field devoted to the promotion of socially desirable behavior. We focused on the promotion of pro-environmental behavior. The decision whether or not to behave environmentally friendly confronts the individual with a social dilemma. This is a choice between an option that serves the collective interest and an option that serves his or her self-interest. Choosing the environmentally friendly option is in the interest of others (e.g., the community, society, even future generations) but is often associated with a cost to the individual, like money, time, effort, or inconvenience. Therefore, convincing an individual to behave environmentally friendly implies persuading him or her to pursue the interest of others at the cost of his or her immediate self-interest. The social marketing approach traditionally relies on the assumption that successful behavioral change towards serving the collective interest, directly follows from having people think about the consequences of behavioral alternatives. Informational and educational campaigns based on this idea have indeed been very successful at generating awareness and concern about environmental issues, but, in contrast, disappointingly unsuccessful at making people change their behavior. We propose an complementary approach that consists of activating the right pro-environmental value in a more subtle way. We found, using laboratory games with a social dilemma structure, that decisions can be based on either an intuitive or a more rational system. People with pro-social values tend to behave more pro-socially than people with pro-self values when they followed their intuitive system. However, when thinking more rationally, pro-socials and pro-selfs behaved equally selfishly. Thinking seems to enable individuals to find justifications for behaving selfishly. Therefore we present two persuasion techniques, which do not motivate people to think, but which simply suggest or remind people that they hold pro-environmental values. Positive cueing reminds people of cases in which they behaved pro-environmentally in the past, and social labeling describes a person as being concerned with the environment. Both tools were more successful at producing more environmentally friendly behavior than educational campaigns.