A problematic way to think about social categories is to essentialize them--to treat particular differences between people as marking fundamentally distinct social kinds. From where do these beliefs arise? Language that expresses generic claims about categories elicits some aspects of essentialism, but the scope of these effects remains unclear. This study (N = 204, ages 4.5-8 years, 73% White; recruited predominantly from the United States and the United Kingdom to participate online in 2019) found that generic language increases two critical aspects of essentialist thought: Beliefs that (a) category-related properties arise from intrinsic causal mechanisms and (b) category boundaries are inflexible. These findings have implications for understanding the spread of essentialist beliefs across communities and the development of intergroup behavior.