Scientists and policy makers face significant challenges when attempting to engage the public about climate change. An important first step is to understand the number and nature of the audiences one plans to target—a process known as audience segmentation. Segmentation involves identifying, within an audience or target population, homogenous subgroups that share similar demographic and/or psychographic profiles. After segmenting an audience, climate change communicators can target their messages based on the unique characteristics of each subgroup. For example, to stimulate engagement and behavior change, messages aimed at audiences that are skeptical about climate change may require different content and framing than messages aimed at audiences already deeply concerned about climate change. The notion of matching message content to audience characteristics has a long history, dating back to the Ancient Greeks. More recently, audience segmentation has played a central role in targeted advertising and also social marketing, which uses marketing principles to help “sell” ideas and behaviors that benefit society. Applications to climate change communication are becoming more common, with major segmentation and communication initiatives being implemented across the globe. Messages crafted to meet the needs of specific audience segments are more likely to be read, understood, and recalled than generic ones, and are also more likely to change behavior. However, despite these successes, the approach has not been uniformly embraced. Controversies have emerged related to the cost effectiveness of segmentation strategies, choice of segmentation variables, potential effects related to social stigmatization, whether segmentation encourages shallow (as opposed to deep) change, the extent to which segments are “found” as opposed to socially constructed by researchers, and whether interindividual differences are best conceptualized in terms of categories or dimensions.