Survivors and families of those killed in the Claudy bombings 50 years ago will gather in the quiet village of Co Derry later to mark the anniversary.
An intercommunity service with readings and hymns will be held at the village memorial.
Nine people, Catholics and Protestants, were killed and 30 injured when three car bombs exploded in the village on July 31, 1972.
Among the victims were Kathryn Eakin, nine, who cleaned the windows of the family grocery store, Patrick Connolly, 15, and William Temple, 16.
The adults killed were Artie Hone, 38, Joseph McCluskey, 39, Elizabeth McElhinney, 59, James McClelland, 65, Rose McLaughlin, 52 and David Miller, 60.
The attack was blamed on the Provisional IRA, although the group never claimed responsibility.
No one has ever been convicted for the attack.
Several of the bereaved families are pursuing legal action against the Catholic Church after a 2010 police ombudsman report found a Catholic priest, the late Father James Chesney, to be a suspect.
The report says the police, the state and the Catholic Church covered up his alleged role in the bombing.
Victims’ Group South East Fermanagh Foundation (SEFF) has supported families over the past 12 months by developing a series of projects and events designed to mark the anniversary.
Director of Services Kenny Donaldson said: “We have had a relationship with the Claudy families for several years, but over the past 12 months we have worked collaboratively with the nine bereaved families, injured people, churches, schools and a range of others. in developing a series of events designed to mark a landmark 50-year anniversary.
He added: ‘The Claudy bombings were an attack on the whole community in the area and it came to light with the deaths of nine innocent people, young and old, men and women, Protestants and Roman Catholics – these neighbors died together and Claudy as a small village was forever changed.
“The bereaved families shared their experiences over the past few months with a designated project facilitator resulting in the production of a publication to be launched on the anniversary.
“The schools have also developed a project around digital, working together in partnership looking at the past at Claudy, the present and what they want for the future.
“There will also be a community public service held on Sunday at the Claudy Memorial and in the main car park, starting at 3 p.m..”
SDLP East Derry MP Cara Hunter said the impact of the Claudy bombing still had a profound impact on the region after 50 years.
She said: “My thoughts are with the families of the victims and all those affected as we approach the 50th anniversary of the Claudy bombing.
“The events of that day cast a dark shadow over this village which still remains to this day.
“As a result of this bombing, many families and a community have been torn apart and for many the pain is still as real today as it was when this shameful act was committed.”