Oireachtas is expected to receive group's report on eighth amendment next year
Taoiseach Enda Kenny has described issues due to be discussed by the Citizens' Assembly, including abortion, as "deeply complex, hugely challenging and profoundly ethical".
Mr Kenny was addressing the group's inaugural meeting in Dublin Castle this afternoon.
"Your work in addressing and achieving this vital consensus on behalf of us all will affect - indeed profoundly affect - how we live our individual lives and our national life in the Republic in the years to come," he said.
"Therefore, on behalf of the Oireachtas, I thank each and every one of you for your personal commitment, your civic generosity and above all your courage in contributing to this national discussion of such significant import.”
The Fine Gael leader also called for respect to be shown towards the assembly as it meets over the coming months:
The body is made up of a chairperson, Ms Justice Mary Laffoy, and 99 randomly selected citizens described as "broadly representative" of the Irish electorate.
"On behalf of the Oireachtas, I ask everybody to please allow the members of the assembly the necessary space and respect to go about their work," Mr Kenny said.
"As citizens of this Republic, let us consider the work of the assembly and the issues at hand according to the highest standards of our best selves.
"To do otherwise would be to diminish the assembly and by extension who we are or wish to be as a respectful, tolerant society that welcomes diversity of opinion and the dignified debate that ensues."
A number of opposition TDs and pro-choice groups have criticised the government over its decision to set up the assembly. However, Mr Kenny said it is the right way to approach an issue as "profound" as the eighth amendment:
Today's introductory session is focused on allowing members to meet one another and gain a better understanding of their roles.
Justice Laffoy told the assembly that all members will be encouraged to give their views on each topic:
Discussion of the assembly's rules, procedures and upcoming work programme will be held in private session.
The group is not due to examine the constitutional ban on abortion, which is the first item on its agenda, until next month.
Among the other issues it has been asked to assess are:
A steering group, made up of the chairperson and a number of members, will be set up shortly to support the assembly in its work.
An expert advisory group will also be established to provide information and advice. This will be comprised of academics and practitioners in fields ranging from medicine to constitutional law.
The assembly will meet again on November 25th in the Grand Hotel in Malahide to begin considering the eighth amendment.
Discussions on the topic will continue over a series of meeting before a report on the amendment is submitted to the Oireachtas in the first half of 2017.
Sinn Féin leader Gerry Adams earlier wished the members well, but accused the government of failing to establish an effective mechanism to drive legislative change.
"The constitutional convention worked very well," he said, referring to the body that recommended a referendum on same-sex marriage in 2013.
"It was inclusive and broadly based with citizens and public representatives working together to reach agreement on important constitutional and political matters. The referendum success on marriage equality is just one example.
"Regrettably the government, in framing the citizens' assembly, has insisted on sticking rigidly to a much less effective structure, with no political representation and no voices from the north.
"This failure to appreciate the all-island imperative for future development is a serious mistake by the government."
This afternoon's inaugural session, and future meetings, can be watched live on www.citizensassembly.ie.