President Michael D Higgins has used his inauguration address to stress the need for inclusion, diversity and equality, and to overcome inequality in areas such as housing, health and education.
President Higgins also signalled his intention to support the global conversation on climate change and world poverty.
He also referenced the rights of women, in the centenary year of women gaining the right to vote.
He also addressed violence against women, and separately racism and hatred which he noted had been rejected by young people here.
President Higgins signalled his intention to support the global conversation on climate change and world poverty and the need to turn words into deeds.
During his second term of office a number of significant state commemorations will take place - including the anniversaries of the war of independence and civil war.
He added that while we must not re-open wounds, we must acknowledge the scars.
President Higgins was inaugurated for a second term as President of Ireland in a ceremony at Dublin Castle, where he made the presidential declaration as he was sworn in for another seven years.
"I, Michael D Higgins, do solemnly promise and declare I will maintain the constitution of Ireland.
"I will dedicate my abilities to the service of the people of Ireland," he said.
In attendance at the ceremony were former presidents Mary Robinson and Mary McAleese, Taoiseach Leo Varadkar and Tánaiste Simon Coveney.
All five of the candidates who ran against President Higgins were also in attendance.
President Higgins was the last to arrive, his vehicle preceded by lines of outriders.
He and his wife Sabina were welcomed to Dublin Castle by Mr Coveney. They turned to give the waiting media a smile and wave before entering the castle.
Christian, Jewish and Islamic religious representatives opened the inauguration ceremony with a prayer.
During his inaugural speech, President Higgins thanked those from different political parties and communities who supported his campaign.
"I want to thank you, the people of Ireland, for the honour you have again bestowed on me, an honour I accept with all the energy of mind and heart that is required for the trust your mandate has placed on me," he said.
"I will, I have emphasised, be a president for all of the Irish people, wherever they may be and in whatever circumstances, those who supported me and those who were not among that number.
"We cannot afford to be complacent as to how we are living our lives and planning our future at local, national, European or global level.
"Inequalities are deepening and many of our people do not have the necessary securities of adequate housing, shelter, health, education, such securities and supports which would allow them to realise their rights and participate with equality."
President Higgins added: "A real republic requires a wide embrace, inclusive of all its members - in our case, all of our Irish from different generations including those who are abroad - and it must be generous in its reach."
"We can and must be advocates for the inclusion of diverse peoples, traditions and belief systems in a peaceful world assisted by strong multilateral institutions, themselves supported by a deeper
global consciousness, one derived from the irreducible rights of human dignity."
Mr Varadkar thanked President Higgins’ wife Sabina, and mentioned the couple's beloved dogs Brod and Sioda before thanking President Higgins himself for a life of service to Ireland.
"Throughout a lifetime of public service, President Higgins has spoken for all parts of Irish society, and all of our people," he said.
"As an academic, an artist, a TD, a senator, a minister and as president, he has always articulated a clear set of values and principles, and has spoken with courage, compassion and authenticity.
"By representing us with distinction, he has brought distinction on our country."
Concluding his speech, President Higgins said: "Muintír na hEireann, I thank you again from my heart.
"This is your presidency and I will work for you and with you towards a future of equality, participation, inclusion, imagination, creativity and sustainability.
"It is together that we go forward."
Michael D Higgins was elected on 26 October, with 822,566 votes - 56% of the vote - the biggest personal mandate in Irish history.
Additional reporting: PA