Shelter will take more local authorities to court to help enforce the Homelessness Act, which becomes law in the summer.
Councils have to provide more permanent housing and help to re-house 16 and 17 year olds as a result of the law, said Shelter's policy manager Sarah Kincaid.
Shelter already takes local authorities to court if they refuse to re-house priority groups, and this is likely to increase as a result of the Act, said Kincaid.
Kincaid said: "We want less repossessions if, say, housing benefits have been delayed. A more co-ordinated approach saves money in the long term."
Shelter also looks set to increase its watchdog and advisory relationship with local councils, which are legally required to come up with long-term homelessness prevention strategies from May 2003.