Results at GCSE have shown the biggest increase in top grades since 1999.
More entries got top grades
Of all entries in England, Wales and Northern Ireland, 59.2% were awarded grades between A* and C - a 1.1 percentage point rise on last year.
Girls are continuing to outperform boys, prompting calls for more action to cut the "gender gap".
Fewer pupils are taking French and German but there has been a rise in the numbers taking subjects such as maths, chemistry and physics.
The overall pass rate has stayed the same as last year, with 97.6% achieving grades between A* and G.
Girls out-stripped boys by 5.3 percentage points at grades A* and A and by 8.4 points at grades C and above.
However, the "gender gap" shows signs of narrowing among the best students, with boys' improvement at grades A* to C increasing by 1.3 percentage points compared to 0.9 for girls.
GCSE RESULTS 2004
Pass rate - 97.6% - same as last year
A* to A - up from 16.7% last year to 17.4%
A* to C - up from 58.1% last year to 59.2%
The government welcomed an increase in students taking maths and science courses.
In maths, the proportion getting grades A* to C increased by 1.6 to 51.7% - with a 4.5% rise in the numbr of entries.
There was also a 10% increase in the numbers taking a GCSE in PE.
Chemistry entries were up 5%, while physics and biology rose 5.1% and 4.4% respectively.
Science experts have complained about fewer pupils studying science at school and university.
School Standards minister David Miliband said the results reflected the hard work of pupils and teachers.
"It is encouraging more pupils are taking maths and gaining good grades.
"It is also good to see more pupils taking science," he said.
"Boys are catching up but there is still work to be done. We will carry on with our programmes to bridge the gap. I know schools are working hard to help boys do better each year."
The provisional results were published by the Joint Council for Qualifications (JCQ), which warned they showed the continuing need to motivate boys.
Dr Ellie Johnson Searle, JCQ director, said: "The evidence of boys 'fighting back' against the girls at A-level is not replicated at GCSE.
"When we look at the total school population at GCSE, there is no evidence either this year or over the past seven years that the gap is narrowing."
Head teachers say students and teachers should be congratulated on the results.
John Dunford, general secretary of the Secondary Heads Association, said: "Schools have put a lot of work into raising boys' achievement and this is now being reflected in a narrowing of the gap between boys and girls at grades A* to C.
But heads said the fall in pupils studying GCSEs in French (down 3.9%) and German (down 2.9%) was worrying.
Spanish proved more popular, with entries rising 4.5%.
Modern languages were made voluntary for 14 and 15 year olds last year.
MOST POPULAR GCSE SUBJECTS
Science: Double Award
Design and Technology
There were regional variations in GCSE performance.
In Northern Ireland, 69.4% received grades between A* and C. In England, the figure was 58.7% and in Wales 60.7%.
Pupils in Northern Ireland received some results on Tuesday, but had to wait until Thursday for results of exams taken with English exam boards.
The Conservatives say there should be less coursework and more emphasis on improving pupils' basic skills.
The Liberal Democrats want GCSEs to be scrapped.