On January 1 1973, the then Irish Taoiseach (or Prime Minister) Jack Lynch signed Ireland into the European Economic Community (EEC) alongside the UK and Denmark.
Despite a difficult start, Ireland has gone from being poor to being one of the wealthiest countries in the world per capita, thanks mainly to EU membership.
Speaking to Euronews, former Taoiseach and EU Ambassador to the US John Bruton said: “EU membership took Ireland out from under the shadow of our near neighbour Britain and enabled us not just to be independent politically but independent economically. EU regulations helped modernise our economy. EU funds were vital to the upgrading of the infrastructure of Ireland, transport and other areas as well.”
The value of Irish goods has jumped from 3.5 billion (Irish) pounds to €120 billion.
The population has increased from 2.9 million to just over 5 million people.
Participation in third-level education currently stands at 63% compared to the OECD average of 59%.
In 2013, Ireland went from being a recipient of EU funds to being a net contributor.
Ireland first applied for EU membership in 1961 and again in 1967. The Accession Treaty followed a period of intense negotiations, which began in September 1970.
In 1972, a referendum was held and a large majority of the Irish people endorsed the motion to join the EEC. Turnout was high at 70.3% and four out of five people (83.09% of the electorate) voted in favour.
But not everyone loves the EU
Despite the huge economic benefits felt by the country, not all sections of Irish life welcome membership.
Participation in the agri-food sector has fallen in the last 50 years, much to the disgust of those in the Irish fishing sector.
Once abundant in fish like cod and salmon – Ireland has experienced overfishing from overseas trawlers.
“I believe that we have given far more to the EU than we have ever received," says Thomas Pringle, an Independent TD in the Irish parliament.
"I come from Killybegs which is the largest fishing port in Ireland and what we have given over in terms of fishing rights and fishing resources to the EU since we joined, dwarfs anything we have received from the EU in agricultural payments or in structural funds or anything like that. I think it has destroyed the country.”
A modern Ireland
From a gloomy recession in the 1980s to the Celtic Tiger boom of the 1990s & 2000s, it took Ireland two decades to catapult from an agriculture-reliant economy to housing some of the world's biggest tech multinationals.
The country still faces challenges today – in the face of managing resumed talks with the UK over the Northern Ireland Protocol, homelessness figures rising, a housing crisis and maintaining peace with Northern Ireland.
The Irish success is a reminder though to all countries hoping to join the EU that if their application is successful and they spend their Brussels money wisely, they too can enjoy similar prosperity in the years and decades to come.