Research in pediatrics raises fundamental ethical questions and has led to quite sophisticated discussions and regulatory responses. One of the more contentious set of issues surrounds the question of whether children can participate in the decision about whether they should be research subjects. Obviously, very young children cannot. But as children get older, they become more capable of understanding the risks and benefits of research. They are not legally empowered to give consent, as adults are. But neither should their values and preferences be ignored. The American Academy of Pediatrics and the federal Office of Human Research Protections both require researchers to seek the assent of children when the children are capable of giving assent. Not everyone agrees, however, when children are capable of assenting or when their assent should be sought. Our PowerPoint reviews the controversies that led to the development of the concept of assent as well as some of the vagaries surrounding the concept today.