In response to environmental challenges, advocacy organizations are seeking optimal ways to increase public engagement. In this talk, Prof. Hart will discuss how different message strategies may amplify or attenuate public engagement. Prof. Hart will first present findings from recent studies investigating how positive and negative sentiments in advocacy messages, delivered via email and Facebook, relate to public engagement. The studies reveal that for low-effort engagement, positive sentiment is associated with more engagement. However, for high-effort engagement, negative sentiment is associated with more engagement, whereas positive sentiment is associated with less. Prof. Hart will also share results from an experiment examining how news articles discussing climate change's unequal impacts, based on race versus class, affect beliefs and support for action. Overall, White participants and those with high levels of symbolic racism had lower levels of belief and support when exposed to the race-focused condition. The results suggest that highlighting class-based climate disparities may be less prone to causing backfire effects.