The “child as scientist” metaphor has been a source of many important insights about how children learn about the world. Extensive research has shown that, like scientists, children construct and test theories about the world through observation, exploration, and experimentation. What is not known, however, is whether children are similar to scientists in their employment of thought experimentation and other rationalistic processes when trying to learn about the world. Although the history of science has documented many instances of thought experiments being central to conceptual revolutions, there have been no empirical studies that ask the same question within developmental psychology. Such empirical studies are needed and warranted. Contrary to popular belief, children’s imagination is not fanciful or poorly disciplined. Instead, their imagination is constrained by knowledge of causal principles across different domains. Thus, engaging children in thought experiments should not produce unrealistic or impossible outcomes; rather, it should produce outcomes consistent with the causal structure of the world. Indeed, the consideration of hitherto unacknowledged implications of such outcomes may teach children something new about the world. This chapter reviews evidence from several studies that were not originally designed to test whether children can benefit from thought experiments but which nonetheless provide encouraging preliminary evidence of such benefit. Somewhat surprisingly, they hint that at least under some circumstances, the benefit from thought experiments may be greater than the benefit from direct observations of the world.