The number of young people not in work, education or training stands at more than one million - virtually unchanged since last year.
The skills minister said the figures included the lowest comparable level of 16 to 18-year-olds for 13 years, but union leaders said the data "shamed" the Government.
There were 1.09 million 16 to 24-year-olds in the UK not in education, employment or training (Neet) in the quarter to June, down by 1,000 from the first three months of the year and by 104,000 from a year earlier.
The percentage of young people classed as Neet was unchanged at 15.1%, said the Office for National Statistics.
Just over half of the young people were looking for work, so were classed as unemployed, with the rest either not looking for or available for work - known as economically inactive.
Skills minister Matthew Hancock said: "With GCSE results out today, I am heartened to see the fall in the number of young people not in work, training or education. We are heading in the right direction, but one young person out of work, education or training, is one too many.
"That is why we are continuing to work hard to give young people the skills, confidence and experience demanded by employers and universities. Only then can we say we have done everything we can to ensure young people reach their potential and help us compete in the global race."
Dave Prentis, general secretary of Unison, said: "The slow rate of progress in getting our young people into work, education or training shames this Government. Every statistic represents a young person who is being given no hope for the future.
"The number of youngsters leaving school, colleges and universities will swell the ranks of Neets adding to the need for more help and support. Instead, our young people are being let down by Government cuts to careers services, high youth unemployment and the rocketing cost of continuing education."
Len McCluskey, Unite general secretary, said there was "no cause for celebration" over the figures, adding: "These figures tell a million stories of untapped potential and dashed hopes thanks to a government that has made it harder and harder for our young people to make a start in life.
"Its disastrous handling of the economy means all it is prepared to offer our young people is an insecure future of low paid employment, creating a lost generation with no hope and no future.
"Our young people are not a pool of cheap labour - they are meant to be our citizens of tomorrow. They need to be offered more than despair, they need a stake in our society, which comes by investing in them through apprenticeships, education, vocational training and decent jobs."
The Government pointed to figures showing that the proportion of 16 to 18-year-olds classed as Neet was 9.1% (168,000), a drop of 1.4% over the same period last year.