In 1848, the Girls' Normal School was established as the first secondary public school for women in Pennsylvania. It was also the first municipally supported teachers' school in the U.S. The first instructional session was held on February 1, 1848. By June 1848, there were 149 enrolled students, an incredibly large enrollment for a school at that time. The school continued to grow, forcing a move in 1854 to Sergeant Street between Ninth and Tenth Streets.
In April 1854, the name of the school was changed to the Girls' High School of Philadelphia. By June 1860, 65 graduates had received diplomas bearing the Girls' High School name. In 1860, the name of the school was again changed to The Girls' High and Normal School to better define the "design of the institution" as a school for an education confined to academic subjects and for future teachers.
In October 1876, a new school which "for convenience and comfort will probably have no superior" was constructed at Seventeenth and Spring Garden Streets. At the time it was surpassed in size only by Girard College and the University of Pennsylvania.
In 1893, the High School and Normal School were separated into two distinct institutions. It was at this time that the institution became known as the Philadelphia High School for Girls. The school offered three parallel courses: a general course of three years with a possible postgraduate year, a classical course of four years, and a business course of three years. In 1898, a Latin-Scientific course "was designed to prepare students for the Women's Medical College, Cornell, Vassar, Wellesley, Smith, Barnard, or such courses in the University of Pennsylvania as were open to women."
In the early 1930s, the school survived attempts to merge it with William Penn High School. Alumnae, faculty and friends of the school dedicated themselves to its preservation. The school emerged from this crisis with its current identity as a place for the education of academically talented young women.
In 1933, a new school was erected at Seventeenth and Spring Garden Streets to replace the one which had stood on the site since 1876. This historic building, now the site of Julia R. Masterman School, was added to the National Register of Historic Places in 1976.
In May of 1976, Vice Principal Dr. Florence Snite sued Katherine Day for libel because she had organized a demonstration protesting the administration's policy which barred lesbian alumnae from attending the prom.
In 1958, the school again outgrew its location and moved to its current site at Broad Street and Olney Avenue. Located down the street at Ogontz and Olney Avenue is Central High School, which, until 1983, was an all-male school. Prior to Central turning co-educational, the two schools enjoyed a strong partnership.
Graduating classes at Girls' are known not by class year (e.g., "the class of 2008") but rather by class number (e.g., "the 252nd graduating class"). This is because of the former practice of semiannual graduation. As annual graduations were instituted, the practice of referring to class numbers remained.
Many fine traditions have survived Girls' long history. Annual celebrations include Contest and County Fair. Graduation traditions also continue. Girls' High graduations were formerly held at the Academy of Music. Currently, they are held at the Kimmel Center for the Performing Arts. Students wear white dresses no higher than knee length and carry red flowers. The students purchase their own dresses in any style but the rules of color and length are enforced.
Due to budget cuts, Girls' High will now be losing staff including counselors in the 2013-14 school year. Also, some clubs may be eliminated from the school.
As of 1984, Girls' High had the unique distinction of being the only high school in the U.S. to have had three graduates selected as White House Fellows since the program was started by President Lyndon B. Johnson in 1964.
In 2000, the school had its first Million Dollar Scholar. She received a perfect grade-point average and was offered $1 million in college scholarships.
- Big Sister, Little Sister – Seniors are paired with incoming freshmen and act as their "big sisters". The "big sisters" provide transitional support to their "little sisters".
- Freshman Day, Sophomore Day, Junior Day – Each class is given a day to honor it. Students of the honored class generally sport flowers in their class color, host an auditorium show, and have a tea or other social gathering.
- Senior Day – Graduating seniors are given awards for their academic and extracurricular achievements. After the awards ceremony they have lunch, often on the Spirit of Philadelphia or at the Chart House.
- Contest – started in 1913 and has evolved over the years. The seniors and freshmen team up to compete against the sophomores and juniors in a variety of competitions that span a few weeks.
- County Fair – A schoolwide all-afternoon fair in which each advisory class contributes food, games, and entertainment. All the money earned during county fair is given to a charity of choice by the winning advisory.
- Songs of the Season – The school's holiday show. The program begins with the procession of members of the school's Treble Clef Choir through a completely dark auditorium. Each choir member carries a single lit candle and chants "Hodie Christus Natus Est" by Benjamin Britten. The show continues with holiday performances by the school's various extracurricular groups and ethnic clubs. Jill Scott (a Girls' High alumna) made an appearance at Songs of the Season in 2006.
- Career Day – Alumnae return for a day to give presentations about their careers.
- Holiday Open House – Every year, alumnae return to the school for a Holiday Open House. This is held in the pink marble hall with the Nike of Samothrace or Winged Victory, which is the symbol of Girls' High, at one of the hallway and Abraham Lincoln at the other.
- All Alumnae Reunion Luncheon/Meeting – Alumnae from all class years gather together to network with each other. The guest speaker is usually a distinguished alumna. There is also a performance by a student group.
- Graduation – ceremony at the Academy of Music, and now at the Kimmel Center. All graduates wear white dresses and carry a bouquet of red carnations.
Additional school events
- Father-Daughter Dance
- Winter Dinner Formal
- Soph Hop
- Junior Prom
- Senior Prom
- Zero Day
- Junior Book Awards
- Move Up Day
The school song has two parts. Alma Mater was written by Grade Gordon (1906) with music by F. Edna Davis (1906). Fidelitas was written by Emily Loman in June 1915.
Beginning in 2011, students were required to wear school uniforms of black pants or below-the-knee skirt with either a white polo with school logo or a "spirit shirt" (has the school name and/or logo; available in the school store). Students no longer have to wear school uniform, but there is a dress code that the students are to follow
- Erika Alexander - actress
- Gloria Allred - attorney
- Tanya "Rafika" Anderson - U.S. diplomat, Consul General Barcelona (218, 1974)
- Hon. Lisa Richette (Lisa Aversa Richette) - judge, author, social activist
- Deborah Batts - federal judge
- Elaine Brown - first woman head of the Black Panther Party
- Barbara Chase-Riboud - author and artist
- Shirley Clarke Franklin - first woman Mayor of Atlanta, Georgia
- Constance Clayton - first woman and first African American Superintendent of Schools in Philadelphia
- (Muriel) Patricia Gilliam Clifford - contributing columnist to the Philadelphia Tribune
- Edith Grossman Ph.D. (Edith Dorph Grossman) - translator of modern Latin American literature
- Tina DiFeliciantonio - filmmaker; partner in Naked Eye Productions Ltd.
- Buntzie Ellis Churchill - president of World Affairs Council
- Leslie Esdaile Banks - novelist
- Sara Garonzik - Executive Producing Director Philadelphia Theatre Company (212, 1968)
- Margaret Gatter Payne - Lutheran bishop
- Marlene Gerber Fried - Professor of Philosophy and Interim President of Hampshire College; reproductive health, rights and justice activist
- Patricia Giorgio Fox - Deputy Police Commissioner
- Julie Gold - Grammy-winning songwriter, singer (218, 1974)
- Pinkie Gordon Lane - first African American poet laureate of Louisiana
- Ann Hobson Pilot - principal harpist, Boston Symphony Orchestra
- Linda Lieberman Dennery - newspaper publisher
- Tina Sloan Green - athlete
- Helene Hanff - author, 84 Charing Cross Road
- Barbara Harris - first woman ordained a bishop of the Episcopal Church
- Judith Harris - attorney
- Ida Augusta Keller - plant physiologist; taught at the school, 1893–1930
- Candice Anitra Manson Weinstock - musician 
- Ayana Mathis - author of The Twelve Tribes of Hattie
- Dr. Philomena (Innocenti) McAndrew - oncologist
- Janet Klein - Pennsylvania Historic Commission
- Virginia Knauer - presidential economic advisor
- Hon. Dolores Sloviter (Dolores Korman Sloviter) - first woman named Chief Judge Of the US Court of Appeals, Third Circuit
- Amy Li - photographer (250, 2006)
- Hon. Frederica Massiah-Jackson - President of the Court of Common Pleas, Philadelphia
- Khanya Mkhize - actress 
- Dr. Donna Mildvan - doctor of infectious disease medicine; one of the first to recognize AIDS as a new disease
- Bebe Moore Campbell - author
- Wanda Nesbitt - US Ambassador to Namibia (218, 1974)
- Vanessa Northington Gamble - physician; authority on public health
- Barbara Nissman - pianist in the grand Romantic tradition
- Susan Orr Braudy - author and Pulitzer nominee
- Carolann Page - soprano and actress, Broadway, Off-Broadway, opera (212, 1968)
- Howardena Pindell - artist, author
- Sharon Pinkenson - director of the Philadelphia Film Office (210, 1966)
- Jonelle Procope - president of the Apollo Theater Foundation (212, 1968)
- Jessie Redmon Fauset - Harlem Renaissance novelist; editor of The Crisis
- Blondell Reynolds Brown - Philadelphia City Council member
- Sharon I. Richie - White House Fellow, 1982-1983
- Margie Samoff - Director of the Prince Theater (Philadelphia)
- Jill Scott - pop artist
- Lisa Lopes - member of the best-selling female American group of all time, TLC
- Ilene Plato - restaurateur
- Judith Rodin (Judith Seitz Rodin) - first woman President of the University of Pennsylvania; President of the Rockefeller Foundation
- Mary Schmidt Campbell - president of Spelman College
- Marietta Simpson - mezzo-soprano
- Zoe Strauss - photographer
- Sandra Strokoff - first woman Legislative Counsel of the House of Representatives
- Beth Stroud - human rights activist, Methodist Church
- Dr. Valarie Ena Swain-Cade McCoullum - Vice Provost of the University of Pennsylvania; first female president of the Cheyney University of Pennsylvania
- Janet Theophano, Ph.D. - Professor of Folklore, Folklore & Education, Folklore & Aging
- C. Delores Tucker - civil rights activist
- Oren E. Whyche - White House Fellow, 1983-1984
- Evelyn Wiener, M.D. - Executive Director of the University of Pennsylvania Student Health Service; physician
- Lisa Yuskavage - artist (224, 1980)
- Patricia Guth - musician, founder of the Bucks County Women's Chorus (221, 1977)
- ^ "Girls HS". National Center for Education Statistics. Retrieved November 11, 2017.
- ^ HQ75. P55x. Philadelphia Gay News. January 3, 1976 – March 25, 1978. Vol. 1. No. 1 – Vol. 2. No. 6. Special Collections Research Center in Temple University Libraries, Philadelphia, Pennsylvania.
- ^ "School Songs." Philadelphia High School for Girls.
- ^ Creese, Mary R. S. (1998). Ladies in the Laboratory? American and British Women in Science, 1800-1900: A Survey of Their Contributions to Research. Lanham, MD: Scarecrow Press. ISBN 0-8108-3287-9.
- ^ Stone, Witmer (2 December 1932). "Ida Augusta Keller (1866-1932)". Bartonia (14): 59–60. Retrieved 30 October 2014.
- ^ "Archived copy". Archived from the original on 2013-09-14. Retrieved 2013-12-07.
- ^