Summary: The relation between science and religion has traditionally been portrayed as a conflict. At the heart of this conflict thesis is the belief that science and religion are two fixed categories of knowledge that are incompatible, and thus an increase in one would necessarily lead to a decrease in the other (Evans, 2018; Harrison, 2015). This belief draws on the assumption that humans strive for logical coherence and consistency, which implies that scientific and religious ways of explaining natural phenomena cannot coexist in the same individual or group. There is growing evidence, however, indicating that this assumption is inaccurate: The same individuals entertain both natural and supernatural considerations that are seemingly contradictory when thinking about natural phenomena such as death, illness, or evolution (Legare et al., 2012). How such coexistence thinking emerges and progresses from childhood to adulthood, however, is largely unknown. To address this significant gap, we will conduct 2 studies that will explore how children and adults react when they are presented with two conflicting explanations—one scientific and the other religious or spiritual—of the same phenomenon and how cultural learning colours their reactions. Our overarching goal is to map how natural and supernatural explanations coexist across development and to explore the potential cultural universals and variations in coexistence thinking. We also want to expand the discussion of the relation between science and religion beyond Western culture and Western religions. Our outputs will include peer-reviewed research articles, conference presentations, op-eds for non-academic audiences, and a social-media account dedicated to the project.