In another paper1 the author has commented upon physical growth and discussed the use of standards, growth charts, and indicators of growth progress and maturity. If the principles covered in this paper are kept in mind, the pediatrician and scientists investigating growth may find it useful to refer to a set of standards suitable for assessments of North American white children. To produce a set of standards for the evaluation of growth in the United States poses many large problems. First, in such a large country, geographic considerations are important; comparing a Californian child to Eastern seaboard standards may be misleading. Second, children today are maturing earlier and earlier, and thus they are bigger age for age than children of yester year2-7; hence, it is important to use recently collected data. Third, ethnic factors must be considered; there really is no such things as a typical "North American white child" but data from studies of specific racial groups cannot be used. Clearly, then, with these, and with many other biometric considerations, we are not going to find any data published or unpublished that will give us exactly what we need. The standards that will be given here are therefore a compromise. They represent a collection of the best presently available data, and they are for guidance only, representing patterns of growth. The sources used are listed in Appendix I. It has been shown1 that known ranges of a measurement are more useful criteria in evaluating growth than are norms. Much attention has been given to such ranges in the production of these standards.