"MISSING CHILDREN'S DAY," begun last year about this time, attempted to call public attention to a national problem that had not been adequately recognized as such: the fact that thousands of children are missing from home because they have run away, been "shoved out" by their parents or kidnapped by non-custodial parents or strangers. No one knows the exact number of such children, who until recently were considered largely a problem for state and local authorities.

Sen. Paula Hawkins (R-Fla.) and Rep. Paul Simon (D-Ill.) sponsored legislation last year to establish two national clearinghouses of information, one for listing and describing all missing children and the other for compiling information on the unidentified dead, many of whom are children. That bill became law and has produced results. So has the broader campaign to bring public attention to this subject.

Pictures of hundreds of missing youngsters have been shown on television and in newspapers. Many of these children have been recognized and returned safely to their homes. Police departments throughout the country--the Montgomery and Alexandria police departments are notable in this area--set up education and prevention programs. Victims' rights organizations were encouraged by law enforcement officials to help families who were affected. A high- technology corporation, TRW, has donated computers in Florida and New Jersey so that police will have up-to-the-minute information, including physical descriptions, on all children reported missing in their state. The FBI has taken steps to improve investigations of child kidnapping, even in cases where no ransom demand is made or no element of interstate transportation proved. Investigations of parental kidnapping have also been stepped up.

It has been a productive year, but there is more to do.