This draft guidance is intended to assist those sponsors of new drug applications (NDAs), biologics license applications (BLAs) for therapeutic biologics, and supplements to such applications who are planning to conduct clinical studies in pediatric populations. Effectiveness, safety, or dose-finding studies in pediatric patients involve gathering clinical pharmacology information, such as information regarding a product’s pharmacokinetics and pharmacodynamics pertaining to dose selection and individualization. This guidance addresses general clinical pharmacology considerations for conducting studies so that the dosing and safety information for drugs and biologic products in pediatric populations can be sufficiently characterized, leading to well-designed trials to evaluate effectiveness.