Identifying low-cost, effective methods to influence behavior is of keen interest to social marketers and others striving to bring about social change. Research on material primes (an object or a word present in the individual’s environment) has received little interest from scientists. This field study conducted in France examined whether the presence of a religious symbol could influence the number of individuals who accepted an organ donation card. The study, conducted with 200 males and 200 females, examined the effect of the presence versus the absence of a Christian cross worn by a solicitor on participant’s compliance to an organ donation request. The findings showed that participants exposed to a Christian cross worn by a solicitor complied more favorably with the request addressed by the solicitor. This effect was found among both male and female participants. The presence of the Christian cross could have acted as a prime that led in turn to the activation of further concepts associated with religion such as compassion, support or solidarity, which in turn led participants to accept the organ donation solicitation more favorably.