Research on child development, the design of social policies, and the delivery of human services for children and families reflect three related yet separate cultures. The capacity to navigate across their borders, to understand their different rules of evidence, to speak their distinctive languages, and to achieve credibility in all three worlds while maintaining a sense of intellectual integrity in each, requires respect for their differences and a commitment to their shared mission. The transmission of knowledge from the academy to the domains of social policy and practice is a formidable task. This challenge could be facilitated by a simple taxonomy that differentiates established knowledge from both reasonable hypotheses and unwarranted or irresponsible assertions that are made in the name of science. An investment in effective “cross-cultural” translation offers a potent strategy for enhancing both the generation of new research and the application of cutting-edge knowledge to make a difference in the lives of children and their families.