Increasing environmental problems and the need to obtain public support to help address them make effective appeals in conservation fundraising campaigns indispensable. However, social marketing messages based on data, characteristics of focal species, selfinterest, and moral responsibility tend to work best on targeted, and so limited, audiences. As conservation organizations reach out to broader audiences, they will require strategies that appeal to more potential donors. This paper argues that use of kinship symbolism to describe non-human species should make conservation marketing campaigns more effective. Evolutionary theories of altruism predict the power of kinship-recognition cues in encouraging and reinforcing sacrifice in non-kin, unreciprocated contexts, and these cues can be manipulated in marketing campaigns to protect threatened species and resources. People often behave altruistically toward ''fictive'' kin, and the labeling of non-humans as kin in many traditional, small-scale societies appears to be associated with environmental resource management. Characterizing non-human species, and even non-living resources, as kin to humans in marketing campaigns may promote a willingness to contribute to conservation-related causes.