Nearly half of marriages in England and Wales still end in divorce, official figures show.
Last year, 117,558 couples formally ended their unions, but this marks a fall of 1.7% on the figure for 2010 when 119,589 marriages were annulled or dissolved.
A breakdown of the figures found 10.8 married people in every 1,000 legally separated last year, compared with 12.9 people in every 1,000 in 2001. This takes the divorce rate back to that seen in the 1970s, The Marriage Foundation said.
Analysis of Office for National Statistics figures - based on marriage, divorce and mortality data for 2010 - show an estimated 42% of marriages end in divorce, compared with 45% in 2005. The ONS figures reveal divorce rates are highest among men and women aged between 40 and 44.
But they show a "general decline" in divorce since 2003.
Harry Benson, of The Marriage Foundation, said: "The longer term trend in divorce rates remains downwards. After peaking in the 1990s, divorce rates are very definitely back at 1970s levels. This has nothing to do with fewer people getting married and everything to do with the way couples who do get married are taking it increasingly seriously."
According to a report compiled by the charity in September, divorces initiated by women in the first few years of marriage have fallen by as much as half.
But Marilyn Stowe, senior partner at family law firm Stowe Family Law, suggested the ONS figures - which relate to 2011 - may not reflect current trends and an apparent rise in divorces among couples in the squeezed middle income bracket.
"I am surprised the number of divorces has fallen," he said.
"Our firm has offices around the country and we have all been busier than ever over the past 18 months. If our firm's caseload is anything to go by, 'big money' divorces are not yet at their pre-2008 levels. Meanwhile, divorces in the squeezed middle income bracket have been steadily rising, and I expect that this rise will be shown in next year's statistics."