Last Friday night 40 pupils braved the cold to sleep rough to highlight the plight of the homeless.
Having been sponsored to undertake the 12-hour challenge, the pupils from Year 7-11, raised money for Shelter Cymru - the people and homes charity in Wales.
Given access to cardboard boxes, sheets of polythene and rolls of sellotape, the pupils, who could bring as much as they can carry, were challenged to construct their own shelter and spend the night at the School without their usual creature comforts.
Mrs Jo Gordon Smith, Dyfrig Housemaster said: "This experience certainly made the students aware of how fortunate they are and how important the work of charities, such as Shelter Cymru is. This started out as a Dyfrig initiative, but we were delighted that so many pupils from the other Houses joined us for a very cold and long night!"
Mr Andrew Jones at Shelter Cymru added: "Shelter Cymru can't thank the Cathedral School enough for their support - the pupils were very well behaved and great credit should go to the staff for their exceptional support and enthusiasm."