ABSTRACT Emerging research has demonstrated that the effects of climate change communication are influenced by the message recipient’s perceptions of the message source. In the present study, we extend this previous work into a domain wrought with inferred communicator biases, policy advocacy. Competence and character enhancing source factors, expertise, perceived caring, and salient value similarity are manipulated to assess their impact on one’s likelihood to support a policy advocated by the source. Results from this online experiment (N = 397) suggest that a climate change policy advocate increased policy support when the advocate was described as (a) caring about people like the participant (vs. not caring) and (b) sharing the participants’ salient values for environmental protection (vs. not sharing their salient values). In contrast, policy support was not influenced by information about the advocate’s expertise. These findings provide initial evidence that communication efforts may need to consider source factors beyond expertise and particularly, those related to trusting one’s character when advocating climate policies. Further, such efforts may be most effective when tailored according to values individuals’ associate with a specific environmental issue or situation.