As is well known, Hogwarts has been coed since its founding in 990 A.D. Indeed, two of its founders were women-Helga Hufflepuff and Rowena Ravenclaw-and they created the houses of Hufflepuff and Ravenclaw respectively. (Though it is interesting to note that it was not until 1999 that the Ravenclaw house motto was revised from "Wit beyond measure is man's greatest treasure" to "Wit beyond measure is our greatest treasure.") Women have always been admitted to whichever house they qualified for, and there has never been a quota limiting the number or percent of female students allowed to attend the school or to be in any house, although neither has there ever been affirmative action or a minimum number or percent of women required to attend the school or any house. Indeed, one looks in vain for the oppression on enrollment of women such as there was of other minorities that blots Hogwarts's history, such as the Jewish quotas which lasted from 1926 until 1972. In fact, the first Jewish student at Hogwarts was a woman (Rebecca Silver, admitted in 1878) as was the first black student (Jane Harper, admitted in 1940).
But one must not pretend it was all smooth sailing for women at Hogwarts. There were no Headmistresses at Hogwarts until Elmira Dresselwood was chosen as such in 1350, despite that there were many qualified female candidates before her. And although there have been as many Headmistresses as Headmasters at Hogwarts (see Footnote), and more female students than male in nearly every year (as there are more girls than boys in Great Britain and Ireland, from which the school takes its students) this did not end sexism in itself. For example, Hogwarts did not allow female entrants for the Triwizard Tournament until 1508 (you will recall the first tournament was held in 1294.) It was thought that women were too fragile to successfully compete, although once Hogwarts began selecting female entrants they quickly proved this wrong, with Violet Martin becoming the first female winner in 1516. The first and only female death in the Tournament (though there were a fair few injuries before and since) was that of poor Summer Chipping, trampled by centaurs in 1632. All other sports at Hogwarts have always been coed, with the most notable and enduring sport of course being Quidditch. Who can forget Zelda Templeton's World Cup-winning catch of the Snitch all the way back in 1481? But I digress.
Spells have kept the school free of rape and sexual harassment, although the anti-sexual harassment spell was not cast until 1970, at Headmaster Dumbledore's insistence (his Deputy Minerva McGonagall actually cast the spell.) Equal pay and employment opportunity for Hogwarts staff regardless of gender was required by the Ministry of Magic beginning in 1969, one year before the Equal Pay Act 1970 was passed in the United Kingdom. Formal feminist activism was slower to arrive at Hogwarts, however, with the first women's rights society (simply called the Women's Rights Society) at the school not being formed until the fall of 1999; it was founded by Ramona Starlight and Fiona Fennec. It successfully pressed for courses in Witch Studies, as well as Women's Studies courses as part of Muggle Studies, which both began in 2000.
I shall not bore you with a catalog of influential witches who graduated Hogwarts and their accomplishments, as you are sure to already know them-Minerva McGonagall we have already mentioned, and there are of course Hermione Granger, Luna Lovegood, Artemsia Lufkin (who became the first female Minister of Magic in 1798), Padma Patil (particularly her work as an Auror) and many others. I provide this brief recounting to increase our pride in our lesser-known history, and to demonstrate how far we have come.
Headmistress Phyllis Rosewood, Year 2015
Footnote: Hogwarts Headmistresses are as follows, in chronological order: Elmira Dresselwood (1350-1355), Lucille Leverton (1356-1359), Martine Maquiline (1360-1365), Geneva Gem (1366-1376), Katherine Quinn (1377-1380), Jaqueline Japes (1381-1390), Phyllida Spore (1391-1408), Edessa Skanderberg (1490-1503), Heliotrope Wilkins (1531-1560), Elizabeth Burke (1600-1615), Dilys Derwent(1741-1768), Janet Trumpkin (1769-1782), Marjorie Mandible (1790-1799), Eupraxia Mole (1870-1879), Dolores Umbridge (1996, although not acknowledged by the Headmaster's office at the time), Minerva McGonagall (1998-2012), Morgan Moon (2013, accidental death resulting in short time in office), Alison Featherlight (2014, accidental death resulting in short time in office), and of course myself. Minerva McGonagall was also Acting Headmistress in 1993 and 1997. Those in bold have been noted by name in the works of the Muggle author J.K. Rowling. Rowling has also written that about Minerva McGonagall's terms as Acting Headmistress, that Heliotrope Wilkins was Headmistress of Hogwarts School of Witchcraft and Wizardry sometime before Armando Dippet (who himself, she noted, served until at least 1943) and that Wilkins had her portrait hung in the Headmaster/Mistress's office, thus showing she died while Headmistress. Rowling has also noted that Phyllida Spore died in 1408, that Edessa Skanderberg died in 1503 (also while Headmistress, as shown by her portrait), that Dilys Derwent served as Headmistress from 1741-1768, and that Eupraxia Mole was Headmistress in 1876 (signing a contract that year with Peeves, the resident poltergeist, to get him to behave better). Rowling has also written that Artemsia Lufkin became the first female Minister of Magic in 1798, and much about the lives of Hermione Granger, Luna Lovegood, and Padma Patil, though she has neglected to describe Patil's career as an Auror.