At least one in four children in Cornwall lives in poverty, a report from a group of leading charities says.
Charities warn child poverty can be a blight on country areas too
It says many youngsters from deprived backgrounds have poor diets, are badly clothed and are more likely to suffer from chronic illness in later life.
The charities, including the End Child Poverty Coalition, have a 10-point charter calling for increased benefits.
The report also includes calls for extra grants and financial help with school uniforms and activities.
One definition of poverty being used in the report is a single parent with two youngsters and a weekly budget of less than £175.
Campaigners say child poverty is not restricted to towns and cities but is a blight on many country areas as well.
Camborne Sure Start crèche manager Kim Parker said the struggle to survive could put a heavy burden on parents on benefits or with low incomes.
She said: "It's a big strain. They can't afford to buy shoes and new clothes, and this goes into how their children are feeling.
"If a parent is stressed, children become very unhappy as well."
End Child Poverty Campaign (ECPC) director Jonathan Stearn said: "Poverty will carry on through adult life.
"We know that children living in poverty just don't achieve their full potential. They often do not leave school with qualifications, and that will set them up for life.
"There has been a gradual decline in Cornwall from 28% to 25%, but it is still one in four."
Government agencies said they were trying to help.
Sue Castle, of Jobcentre Plus in Truro, said: "What's preventing someone going to work is the hours and fitting around other commitments that people have to balance.
"There are a lot of people who do want to get back into employment and we encourage employers to look at work/life balance and consider family-friendly policies."