This randomized clinical trial evaluated individual cognitive-behavioral th
erapy (CBT), family therapy, combined individual and family therapy, and a
group intervention for 114 substance-abusing adolescents. Outcomes were per
centage of days marijuana, was used and percentage of youths achieving mini
mal use. Each intervention demonstrated some efficacy, although differences
occurred for outcome measured, speed of change, and maintenance of change.
From pretreatment to 4 months, significantly fewer days of use were found
for the family therapy alone and the. combined interventions. Significantly
more youths had achieved minimal use levels in the family and combined con
ditions and in CBT. From pretreatment to 7 months, reductions in percentage
of days of use were significant for the combined and group interventions,
and, changes in minimal use levels were significant for the family, combine
d, and group interventions.