Studies were included if: (a) they were RCTs, (b) the population comprised parents / carers of children up to the age of 18 where at least 50 % had a conduct problem (defined using objective clinical criteria, the clinical cut - off point
on a well validated behaviour scale or
informal diagnostic criteria), (c) the intervention was a structured, repeatable (manualised) parenting
programme (any theoretical
basis, setting or mode of delivery) and (d) there was at least one standardised outcome measuring child behaviour.