When the Riots, Communities and Victims panel investigated the causes of last summer's unrest, many people they spoke to blamed poor parenting. The panel's report (pdf), released in March this year, talked about the "forgotten families" who "bump along the bottom of society". These troubled families are often cited as a root cause of many of the social problems Britain faces. So who exactly are these families, and what can be done to help them?

When David Cameron pledged to help the 120,000 troubled families in England, it was a figure based on the number that suffer from at least five criteria in a list that includes out-of-work parents, involvement in antisocial behaviour and crime, and children not at school. These families often face a range of other problems – mental and physical ill-health, domestic violence, addiction, isolation, and relationship breakdowns – which are often long-standing and inter-generational. Children from these families are eight times more likely to be suspended or excluded from school than other children, and 10 times more likely to be in trouble with the police.

A new report by New Philanthropy Capital (NPC) shows that these 120,000 families cost society around £9bn per year. Most of this money is spent on taking children into care. There are also costs associated with crime and antisocial behaviour, eviction costs, benefit payments, drug and alcohol dependency, specialist schooling and healthcare. These families face complex and challenging problems, but there are things which can be done to tackle them and reduce the huge cost to society.

The government has made troubled families a priority: in the last year, it has committed an extra £448m to provide intensive support. But these promises, while positive, are still not enough. For example, the commitment to double the Family Nurse Partnership scheme, which works with young, vulnerable first-time mothers, and was highlighted by the riots panel, will only cover 40% of estimated need. Local authorities are expected to provide 60% of the funds to match the government's new investment in troubled families, but it is not yet clear how they will do this.

The current government focus tends to be on crisis support, with families often not referred until problems are out of control. More investment in early intervention programmes is needed. The first year of a child's life is key: influencing social and emotional development becomes more difficult and costly the later it is left. Once problems become entrenched, parents become more resistant to support and the cost of intervention spirals, so it makes sense to tackle problems before they take root.

But early intervention requires long-term investment, with results sometimes only showing up decades later. They don't lend themselves well to the current vogue for payment by results. Additional independent funding, from charitable trusts and foundations could help shift the balance towards preventing problems and help build the evidence needed for government to invest further down the line.

With tight budgets and stretched resources, it is difficult for families to get the right level of support. Experts say it is crucial for families to have one assertive key worker who can get to the bottom of the problems they face and co-ordinate support from other providers. Small caseloads and long-term, intensive support are essential: the most effective interventions provide support for over a year, with workers visiting several times a week. But when funding cuts mean larger caseloads, shorter-term interventions, fewer outreach services, and long waiting lists some families will slip under the radar. There is also evidence that the most vulnerable families are also least likely to use the support available – they may be suspicious of statutory services, fearful of their children being taken away, or put off by negative experiences in the past.

So charities are often an important resource for these families. Charities such as Family Action that work with disadvantaged and socially isolated families, providing all kinds of support to tackle complex problems, with dedicated case workers to co-ordinate it all. They often find it easier to gain families' trust because they are not a government agency, and can draw in volunteers from the local community to support families in trouble. And they can also take risks with new approaches where government can't.

Tackling Britain's troubled families isn't an overnight job. But there are approaches which work, and investing in early intervention now could prevent the next generation suffering the same problems as their parents.

Matthew van Poortvliet is a senior consultant at NPC and author of the report, 'Out of trouble: Families with complex problems'. NPC is holding an event, Avoiding another summer of riots – the role of the third sector in helping troubled families, at the Guardian later this month

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