Dublin Simon has launched a 'Closing the Door on Homelessness' campaign to mark the 50th anniversary of its foundation.
The organisation began as an initiative by Trinity College and UCD students who started carrying out soup runs at night in Dublin city centre in 1969.
It has since grown with branches around the country particularly in Galway, Cork and Dundalk and helps around 12,000 people a year.
Operating on a combination of fundraising and State funding, the organisation provides emergency outreach services as well as long term supported and independent accommodation.
It moved a total of 2,400 people into secure homes last year.
In 1969, the Dublin Simon students carried just two flasks of soup and counted handfuls of people around the city.
The latest count shows over 10,000 people in emergency accommodation nationally and 156 sleeping rough in Dublin.
Sam McGuinness of Dublin Simon said the economic improvement around 2015 fuelled higher rents and the latest upsurge in homelessness.
The organsiation will be running media advertisements as part of its campaign over the coming weeks with creative and public relations agencies donating their services for free.
"Because of the commitment of volunteers, staff, supporters, funders and members of the public, in the months, years and decades that passed, thousands of shattered lives have been rebuilt and saved.
"People are depending on us nationally and it is because of all our work that we can support people to get back on their feet, to rebuild their lives with Simon by their side. We need the public's continued help and support," said Mr McGuinness.
The Simon Community takes its name from Simon of Cyrene who helped Jesus to carry his cross.
The original group was formed in London in 1963 by probation officer Anton Wallich-Clifford who worked in a city magistrates court.
The Dublin group set up its first base on Winetavern Street beside Christchurch in a property owned by the Franciscans. It later moved to Sarsfield Quay.
The group began providing housing in 1976 and full-time rough sleeper teams were established in 1984.