In a robust testimonial to women's achievements, Mrs Shephard told heads of independent girls' schools that the balance had at long last been redressed.
But she warned there was now a danger that it would go too far the other way - and asked them for ideas on how to raise standards among boys. Mrs Shephard told the Girls' Schools Association meeting in Manchester that the trend had implications for the way boys were taught.
She added: "Girls themselves can set an example and encourage their male peers to work hard and value learning and knowledge."
Girls now do better at GCSE and last year nearly 46 per cent gained five or more passes at grades A to C compared with under 37 per cent of boys.
More 16-year-old girls than boys - 82 per cent compared with 78 per cent - continue in full or part-time education and at A-level, girls now score higher in maths, physics and technology as well as English.
Recent American research has shown that girls also score better in basic literacy and that disproportionate numbers of boys are now falling behind.
Margaret Kenyon, president of the GSA, said: "Girls have the good fortune to carry little baggage from the past; as far as they are concerned there is no golden age to hark back to. It is the present and the future that they must live in."
Her own school, Withington Girls in Manchester, recorded the highest proportion of starred-A grades at GCSE this summer, but Mrs Kenyon attacked the starred grade, which was introduced to stretch the high fliers.
"When you introduce a new grade immediately the other grades are downgraded and for girls to come up to you and say sorry I only got seven As and no stars is an absolute nonsense," she said.
"What we predicted would happen is indeed happening. A star-less A-grade is being seen as downgraded, a B as a C and a C as a failure."
Mrs Shephard refused to bow to calls to abolish the starred grade at GCSE, but said she would listen to arguments against its introduction at A-level.
But she added: "I think it is right to have a hurdle in place for the very very able."
* The public school obsession with team games has consigned many pupils to think of themselves as sporting failures, the head of PE at an independent girls' school has claimed.
Jo Everington, head of PE at Queenswood, Hatfield, a Pounds 10,000-a-year boarding school, criticised schools for measuring success in the number of cups, trophies and honours gained each year.
"For too long independent schools have focused on team sports at the expense of a large proportion of their pupils," she said in On The Map, the magazine of the GSA.
"Success was measured if they were regular team players by the number of county, regional and national honours achieved each year along with the number of cups in the trophy cabinet at the end of the season."
Ms Everington warned that compulsory team games at key stage 4 and beyond were a recipe for disaster and said pupils should be able to choose the activities they pursue.