The Duchess of Cambridge said "the cycle of addiction needs to be broken" as she launched a school drugs and alcohol counselling programme.
Kate visited The Willows Primary School in Wythenshawe, Greater Manchester, to launch the project to help reduce the impact of addiction on families.
The initiative is a partnership between charities Place2Be and Action on Addiction with funding from Comic Relief and the Royal Foundation, whose patrons are the Duke and Duchess of Cambridge and Prince Harry.
Kate met staff and volunteers from youth mental health services charity Place2Be, and children who have benefited from its work.
Action on Addiction will train, supervise and support Place2Be counsellors to deliver the programme in school settings across England.
In a speech in the school hall, Kate, who is also patron of Action on Addiction and Place2Be, said: "Addiction is a hugely complex and destructive disease and its impact can be simply devastating. All too often, lives and families can be shattered by it.
"Through my Patronage of Action on Addiction, I feel fortunate to have met a wide range of inspirational people who have overcome addiction. It is so encouraging to see that with the right help - like that of Action on Addiction - it can be conquered.
"But those who are addicted are not the only victims. I have been struck by the profound and deeply damaging impact it has on the children of affected parents.
"Research has shown that children of those who are addicted are seven times more likely to have addiction problems themselves. They are also brought up surrounded by fear, instability and chaos."
Six months' pregnant Kate's bump was visible in an Erdam patterned blue silk floral dress by Sophia Visconti, which costs £1,065, which she complemented with blue suede shoes.