This report is a statement of philosophy, supported by information gleaned from opinion surveys, crash studies and lab- oratory tests and evaluations. It is intended as a guide for the use of administrators, manufacturers and others. It covers the selection of protective devices for children, and provides the technical background for such selection. When a child reaches his third birthday he can continue to use his approved "child seat" - more precisely, his "chair-with- harness", until he is too large for it, which stage may well not be reached until he is 4 years old or more. If an available approved chair-with-harness is too small, the child can use any available child harness or, failing the availability of that, he can use any available seat belt, preferably one of the lap-sash type. Any restraint should be adjusted to have minimum slack. Retractors are invaluable in reducing slack. Booster cushions have been shown by laboratory test to be viable propositions provided they can be restrained in crashes by the child's back or by suitable anchoring devices. Their use with child harnesses or seat belts greatly increases the acceptability of such restraints.