Corruption, poor management and lack of public consultation have hurt repeated efforts by the Kenyan government and donors to improve slums, including Kibera, the country's largest.
Fieldworkers from Urban ARK, a global research programme, studied three projects in Kenya's slums and recommended future projects consult with affected communities in order to improve the chances of success.
"This will ensure a robust understanding of the local context, including its risk dynamics, and enable transparency and accountability," Urban ARK said in a briefing note.
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Kibera, just five kilometres (3 miles) from Nairobi city centre, has seen three major upgrade programmes since 2004, but none has significantly improved slum dwellers' living standards, the researchers said.
One reason is a failure to communicate, said Ezekiel Rema, chairman of Muungano Wa Wanavijiji (MWW), which represents slum residents.
"The understanding of our people of slum upgrading (is that) it means slum evictions. That's why you find when a project is initiated it takes over 20 years to (get going)," he told a forum in Nairobi on Tuesday.
One project Urban ARK studied was the Kenya Slum Upgrading Programme, an initiative by the government and the United Nations' urban development agency UN Habitat to build high-rises for families in Kibera.
The initiative saw about 1,200 families moved from mud homes to apartments, the ministry of housing said. However, it faced lawsuits from slumdwellers angered at irregularities in the allocation process.
Another project, the National Youth Service (NYS) Slum Upgrade Initiative, engaged young people to build houses and toilets, and provide daily cleanup activities in Kibera and other slums across the country.
It was dogged by scandal and eventually closed after tens of millions of dollars went missing, leading the minister of devolution and planning to resign in November 2015.
A third - the Railways Project - tried forcibly to evict people living alongside the railway in Kibera and move them to new housing elsewhere. It was halted after community activists intervened to prevent the evictions.
Future projects to improve slums must include residents' input rather than imposing solutions on them, said Jack Makau, the Kenyan representative of Slum Dwellers International, a network of urban-poor organisations.
"Working with the community is usually the best entry-point," Makau said.