Royals, celebrities and local heroes, who helped their communities, are attending Princess Kate's annual Christmas carol concert at Westminster Abbey.
The Princess of Wales greeted her husband, Prince William, and the couple's children George, Charlotte and Louis outside the Abbey ahead of the service.
The theme of the service, held in the candle-lit Abbey on Friday afternoon, is kindness and showing love to others.
Actors Kate Winslet, Hannah Waddingham and Chiwetel Ejiofor were among the stars joining the British royals.
According to the BBC, the 1,600 guests will hear a mix of carols, music and readings from actors such as Kate Winslet and Chiwetel Ejiofor.
She also met members of the congregation inside the richly-decorated Abbey, speaking to Holocaust survivor Steven Frank, as well as singer Katie Melua, actor Eugene Levy, and TV cook Mary Berry.
The BBC reported that among the guests will be Anna and Jonathan Cordiner, whose daughter died of a brain tumour, and who set up a charity, Kayleigh's Wee Stars, to support families who have a child with a terminal illness.
Ahead of the carol services, Kate said on social media, "The time, care and compassion you give, often quietly and unspoken, and without any expectation or recognition, make an extraordinary difference to the lives of others."
Kate Middleton has been making a gradual return to public life after her cancer diagnosis and chemotherapy.
Catherine recently delivered her first public speech for two years, in which she talked about recognising the "quiet, often invisible work of caring"
Guests arriving at the Abbey were entertained by young musicians supported by the Future Talent charity, co-founded by the Duchess of Kent to widen access to music lessons.
The duchess, who died in September, had been a primary school music teacher and a great supporter of giving more young people opportunities to play music.
The 'Together At Christmas' service, is the fifth such event that Kate has spearheaded.
It heralds individuals across the country who have given their time to help others, and brings people together to "celebrate love in all its forms", Kensington Palace said.
