There is a general consensus in the medical and medical ethics communities against predictive genetic testing of children for late onset conditions, but minimal consideration is given to predictive testing of asymptomatic children for disorders that present later in childhood when presymptomatic treatment cannot influence the course of the disease. In this paper, I examine the question of whether it is ethical to perform predictive testing and screening of newborns and young children for conditions that present later in childhood. I consider the risks and benefits of (1) predictive testing of children from high-risk families; (2) predictive population screening for conditions that are untreatable; and (3) predictive population screening for conditions in which the efficacy of presymptomatic treatment is equivocal. I conclude in favor of parental discretion for predictive genetic testing, but against state-sponsored predictive screening for conditions that do not fulfill public health screening criteria.