More than 2,000 Catholic migrants living and working in London are expected to attend a special Mass to be celebrated at Westminster Cathedral on Monday 4 May.
For the first time, similar services will take place at Westminster Abbey and the Methodist Central Hall (opposite the Houses of Parliament) at the same time, both celebrating the place of migrants in modern British society.
The Catholic Mass coincides with the Feast of St Joseph the Worker and will start at 10.30am. Organisers say it will "reflect the tremendous diversity of London's Catholic community, with music from across the globe."
A number of dignitaries, including the Lord Mayor of Westminster and Ambassadors from the European Union and other countries are expected to attend the Westminster Cathedral event.
The service will be conducted by the outgoing Archbishop of Westminster, Cardinal Cormac Murphy-O'Connor and by Thomas McMahon, Bishop of Brentwood. The sermon will be given by Bishop Pat Lynch, Auxiliary Bishop of Southwark.
This is the fourth 'Mass for Migrants' to have been organised jointly by the Catholic Diocese of Westminster, the Archdiocese of Southwark and the Diocese of Brentwood and supported by their Justice and Peace Commissions.