This study assessed the 8-y stability and change of parent-reported pr
oblem behaviors in 791 children from the general population assessed a
t 2-y intervals with the same standardized procedure, the child behavi
or checklist (CBCL). Problem behaviors were rather stable across even
the relatively long time interval of 8 y. The 8-y stability coefficien
t for total problem score was 0.48, with somewhat higher stability for
externalizing than internalizing problems. Despite stability, problem
behaviors also changed considerably across time. These changes do not
only reflect the increase in chronologic age. The present study showe
d that there are changes in children's problem levels that result from
historical time influences. These secular trends seemed of even great
er importance than aging effects, and reflect a slight increase of the
norm of children's problem behaviors.