There is ample evidence of the power of social influence on pro-environmental behaviors. Beliefs about the conservation behavior of others (descriptive normative beliefs) have a strong positive correlation with one's own conservation actions. However, this relationship has not been investigated much further in terms of possible moderators or involved mechanisms of information processing. The present study examines two potential moderators and draws links to underlying processing mechanisms. We hypothesized that personal involvement with conservation issues and beliefs about other's approval of conservation (injunctive normative beliefs) would moderate the relationship between descriptive normative beliefs and conservation behavior. The sample consisted of 1604 California residents that were recruited through random digit telephone dialing. Results showed that both injunctive normative beliefs and personal involvement moderated the relationship between descriptive normative beliefs and conservation behavior. High personal involvement weakened the relationship, whereas high injunctive normative beliefs strengthened it. We conclude from these findings that descriptive normative beliefs influence conservation behavior through a rather nonconscious, peripheral route of information processing, while personal involvement motivates a more elaborate, central route of information processing.