The present study examined the developmental origin of "blue lies", a pervasive form of lying in the adult world that is told purportedly to benefit a collective. Seven, 9-, and 11-year-old Chinese children were surreptitiously placed in a real-life situation where they decided whether to lie to conceal their group's cheating behavior. Children were also assessed in terms of their willingness in hypothetical situations to endorse lying or truth-telling that benefits a collective but at the same time harms an individual. Results showed that as age increased, children became more inclined to endorse lying in the name of the collective good, and to tell lies for their group themselves. Furthermore, children's endorsement about blue lies in hypothetical situations predicted their actual lying behavior.