Labour have made a tough pledge
Shelter has warned the government it could fail to achieve targets to avoid putting homeless families into bed and breakfast accommodation.
The government wants to largely end the practice by March 2004 - and officials say figures released on Thursday show that it is making good progress.
But Shelter's new director Adam Sampson says the government must continue to "get tough" with local councils.
The charity agrees that the Office of the Deputy Prime Minister had succeeded in reducing the number of families in B&Bs in areas where the practice was most prevalent.
But it warns that unless the pace of progress picks up in other local authorities, the target will not be met.
The charity says B&Bs are the worst form of temporary housing, often cramped, and in poor condition, with families often having to share kitchens and bathrooms.
Thousands of families with children are currently languishing in unacceptable bed and breakfasts
It is often used because of a lack of alternative housing, but Shelter says "a lack of political will" and the ease of managing it can make it an attractive option for councils.
The government has agreed B&Bs should be phased out except as an emergency measure for a maximum of six weeks.
Mr Sampson said: "Thousands of families with children are currently languishing in unacceptable bed and breakfasts.
"Not only does it have terrible effects on their health, wellbeing and children's education, but it is also the most expensive form of temporary housing.
"The government pledged to end this misery by March next year and there is no excuse for any local authority to miss the target."
Barbara Roche Minister for Social Exclusion and Equality agreed that it was "unacceptable for families with children to have to live in B&B accommodation".
"The whole experience of living in a B&B can ruin lives, especially when it impacts upon children," she said.
She highlighted areas such as the London Borough of Newham which had reduced the number of families in temporary B&B housing.
The ODPM said it had made £35m available to local authorities this year and a further £15m in 2003/04.
Government proposals to introduce legislation to enforce the B&B target are also being welcomed by Shelter.