Advances in genetic technology increase the ability to test children and adolescents for late-onset conditions, disease susceptibilities, and carrier status. Genetic tests may offer medical or psychologic benefits but may also create harm; alteration of the child's self-concept or parent-child bonds and risk of stigmatization are examples of the latter. The article examines developmental theories concerning children's ability to make choices as well as informed consent and ethical considerations in genetic testing. Because optimal care requires awareness of the complex psychosocial and ethical issues involved in childhood genetic testing, nurses must be prepared to acknowledge and discuss such issues with families.