Fr Peter McVerry of the Peter McVerry Trust has told crowds at Dublin's May Day march that the Government's housing strategy is not working.
Speaking outside Liberty Hall, Fr McVerry said there is a need for legislation to stop evictions of people until they have alternative accommodation secured.
He also called for a proper rent caps.
Marchers were drawn from many different groups including unions, left wing political parties, housing and homeless associations and charities and other campaigning bodies.
The march travelled from the Garden of Remembrance to Liberty Hall.
The Government has said it is addressing the housing problem. It said Minister for Housing Simon Coveney has secured funding of €5.3 billion for 47,000 social houses to be added to the local authority housing stock by 2021.