Research on psychosocial interventions with children requires attentio
n to developmental principles such as age-specific competence, maturat
ional shifts, increasing cone of relevant contacts, and socioeconomic
context of biological stages. Research strategies that include such va
riables should lead to ecologically sound investigations and the corre
ct selection of outcome variables. A consideration of the specificity
of treatment and controlled design alone are not sufficient to guide t
he study of the psychological treatment of developing organisms and pe
rsons.