成年礼或者成人礼，是指人类为了庆祝其成员长大成人者而举行之礼俗仪式。

中国古代成人礼指冠礼和笄礼，西周就已存在，一直延续到明朝。

周朝贵族男子满20岁时举办冠礼，即加冠，之后可以娶妻。加冠指男性被族群承认，表示其已成人。如果是公室皇室，加冠年纪可以再提前，因为：年幼的帝王若迟迟未行冠礼，会让臣民觉得他还是个孩子，在统治上有所不便。春秋时鲁襄公就是12岁加冠的例子。

周朝贵族女子则是在满15岁举办笄礼，及笄之后可以许嫁。若女子提早许嫁，也可提早行笄礼。若女子到了二十岁都还没许嫁，也应行笄礼，因此时她已是完全成熟的女子，不再适合做女孩的打扮。

Rite of passage is a celebration of the passage which occurs when an individual leaves one group to enter another. It involves a significant change of status in society. In cultural anthropology the term is the Anglicisation of rite de passage, a French term innovated by the ethnographer Arnold van Gennep in his work Les rites de passage, "The Rites of Passage." The term is now fully adopted into anthropology as well as into the literature and popular cultures of many modern languages.