Changes in the regulatory environment affecting pediatric cancer drug development in the United States and the European Union provide unprecedented opportunity to advance the concept of precision medicine to children with cancer. Increasing evidence suggests that new drugs and biologic products directed at molecular targets presumed to be etiologically associated with many adult cancers may well provide therapeutic options for selected subsets of children with cancer despite their histologic and biologic differences. Regulatory requirements for early evaluation of appropriate new drugs for children based on their molecular mechanism of action, rather than the specific clinical indications for which they are developed and/or approved, will shorten the unacceptable time lag between first-in-human and first-in-children studies. The relative scarcity of pediatric patients eligible for biomarker-directed studies and the ever-expanding compendium of new targeted agents mandate rational, science-based decision-making in selecting and prioritizing appropriate drugs to study early in development. A critical component of the evidence base in such decision-making includes preclinical testing of relevant drugs in pediatric tumor-specific in vitro and in vivo models. Established preclinical testing programs with academic investigator-industry collaborations are actively engaged in such activities. International collaboration is required to address the resource constraints and increasing number of potential products to be tested in a timely, efficient, nonduplicative, and cost-effective manner.