Syosset High School (SHS) is a public high school located in Syosset, New York, United States, in Nassau County, on Long Island. It serves as the public high school for residents of the Syosset Central School District. Syosset High School is the winner of numerous accolades, and as of 2024 was ranked the #12 high school in New York and #128 in the United States by niche.com.

As of the 2021–22 school year, the school had an enrollment of 2,234 students, with approximately 559 students per graduating class, and 214.9 classroom teachers (on an FTE basis), for a student–teacher ratio of 10.4:1. As of 2024, the student body had approximately 49.2% minority enrollment; 50.8% of students were White, while 42.0% were Asian, 5.0% were Hispanic, 1.3% were Two or More Races, and 0.7% were Black. There were 213 students (9.5% of enrollment) eligible for free lunch and 20 (0.9% of students) eligible for reduced-cost lunch.

The school district as a whole was the 2002 winner of the Kennedy Center Alliance for Arts Education Network and National School Boards Association Award, which honors school districts for excellence in arts education. Syosset was also named a Grammy Signature school for its music programs in orchestra, band, and chorus. In 2010, it was rated 14th in the country for music education by the National Association for Music Education. Syosset High School ranked 143rd of 1600+ schools listed in Newsweek's 2010 Best High Schools list.

Eleanor Roosevelt was among the first notable people to make a personal appearance in the auditorium.

In April 2007, the school's Quiz Bowl team won an online national championship.

The Castle Program is designed for students (non-special education) who need a different environment in order to succeed. These students typically have a history of poor class and school attendance. They meet in a separate setting with small class sizes and a close-knit team of teachers who focus on "realistic expectations." Participation in this program is voluntary.

WKWZ, 88.5 FM, is a broadcasting station owned and operated by the Syosset Central School District that operates from 2:30–11:00 pm Monday through Friday. It is licensed by the Federal Communications Commission (FCC). WPOB broadcasts on the same frequency from 7:00–2:30 from Plainview-Old Bethpage John F. Kennedy High School, and is the sister station to WKWZ. The General Manager is head of the Syosset Film and Radio department, David Favilla, with all other positions (other than General Manager, Station Supervisor and Chief Engineer) operated by students in the school, with positions such as Station Managers, Music Director, Sports Director, Traffic Director, Program Director, Community News Director, and Organizational Supervisors.

The boys' swim team has been undefeated since the 2015-16 season, going 70-0 in the dual meet season as of 2023. The team won its 5th straight Conference 1 title and Nassau County Championships in 2019, 2021, 2022. The football team won the 1974 New York State Championship and the Long Island Championship in 2014.

• The girls' soccer team won the Nassau County Championships in 2018.
• The tennis team won the Nassau County Championships in 2015, 2016, 2017, and 2018. They won the Long Island Championship in 2017 and 2018. They had 3 consecutive undefeated regular seasons from 2015-2017. The Syosset Boys Varsity tennis team has consistently been the top, and most competitive, high school tennis team in Long Island since 2015.
• The boys' lacrosse team won the Long Island Championship in 2008 and 2015.
• The girls' lacrosse team won the Nassau County Championships in 2015.
• The boys' cross country team won ten back-to-back Nassau County titles from 1996 to 2006. The cross country and track and field teams have won eleven back-to-back county titles from 2012 to 2016. On February 5, 2005, athletes Chris Howell, Adam Lampert, Dan Tully and Sean Tully set the national indoor record in the 4 × 800 metres relay in a time of 7:42.22. The same team won national championships at the National Scholastic Indoor Championships and Nike Outdoor Nationals and won the 4 × 800 metres relay at the prestigious Penn Relays on April 29, 2005.
• The boys' soccer team won the Nassau County Championship in 2012.
• The boys ice hockey team won the Nassau County Championship in 2015.
• The Girls Varsity Gymnastics team won the Nassau County Championship in 2019, 2021, 2022.
• The Co-Ed Track and Field Team won the Nassau County Championship in 2019

In the 1970s, SHS was known for a unique program called Substitute Enrichment Program, considered innovative at the time. Rather than call in substitute teachers, the funds that would have gone to pay the sub were used to help bring in special guest speakers and class-long programs. When a teacher was absent, students had the option to attend the Sub Program or go to study hall. Run by a staff advisor and a team of student volunteers, the programming was often quite notable. At times, teachers worked the program's contents into their class and brought their classes to the session. Students that attended SHS in the early 1970s remember seeing Issac Asimov, talking with the late Harry Chapin in the "Little Theater." Programming included sports figures, artists, even learning to decorate cakes.

In the 2010s, Syosset students created a program titled, Breaking Borders. This program works to mitigate the racial and socioeconomic boundaries on Long Island. Its mission statement reads, "Breaking Borders is a leadership program that aims to eliminate ethnic, socio-economic, racial, and religious barriers which separate students from different Long Island districts. Through structured conversations with students from other school districts, Breaking Borders enables its members to challenge their biases and opinions by exposing them to new perspectives on important issues, such as race, religion, gender, and privilege". When asked about why Breaking Borders was created, the founders noted that Long Island is one of the most segregated parts of the United States due to a long history of racism due to housing and community planning, and that in the 21st Century that should be fixed. The name Breaking Borders comes from the idea that students work to "break" the "borders" between their peers from various communities around Long Island. Today, the program has significantly grown to include schools from all around Long Island. Some of the schools include Freeport, Elmont, Massapequa, Division High School, and MacArthur High School. Today, the program is more successful than ever as student leaders plan multi-school meetings once a month where members of the program can speak to each other and work to "break borders."

This article's list of alumni may not follow Wikipedia's verifiability policy. Please improve this article by removing names that do not have independent reliable sources showing they merit inclusion in this article AND are alumni, or by incorporating the relevant publications into the body of the article through appropriate citations. (May 2019)

• Judd Apatow (born 1967), screenwriter, director, and producer
• Lesley Arfin (born 1979), television writer and author, Girls, Love, Brooklyn 99
• Vito Arujau (born 1999), NCAA Division I All-American wrestler
• Jay Bienstock (born 1965), Emmy award-winning television producer of Survivor, The Apprentice, and The Voice
• Sue Bird (born 1980) Israeli-American Women's National Basketball Association point guard, four-time WNBA champion, five-time Olympic champion, thirteen-time All-Star (Seattle Storm) (She attended Syosset High School but graduated from Christ the King Regional High School)
• Alan Blinder – economist, author, and former Vice Chairman of the Board of Governors of the Federal Reserve System
• Rosa Brooks – writer, law professor, former Department of Defense staff member (formerly known as Rosa Ehrenreich)
• Elaine Chao – former Secretary of Transportation, former Secretary of Labor, first Asian-Pacific American woman to be appointed a cabinet member
• George Drakoulias – music producer, music supervisor
• Ben Ehrenreich – journalist and novelist
• Alan Eichler – theatrical publicist, producer and talent manager
• Sibel Galindez – actress
• Paul Ginsparg – physicist
• Jerry Gershenhorn – historian
• Brooke Gladstone – journalist and media analyst
• Wayne Gladstone – writer and humorist
• Rick Hodes – medical doctor known for work in the developing world
• Brenda Howard – political activist
• Michael Isikoff – Newsweek journalist
• Kathleen Kim – puppeteer behind the Sesame Street character Ji-Young, the show’s first Asian American Muppet
• Mitchell Lazar – physician-scientist
• Kenneth Lin – playwright
• Jon Lovett – former Presidential speechwriter for Barack Obama and current podcast host
• Carolyne Mas – singer-songwriter
• Robert Maschio – actor, Scrubs
• Idina Menzel – actress and singer
• Ed Newman (born 1951), National Football League All-Pro football player
• Mac O'Keefe (1998) Premier Lacrosse League National Lacrosse League All Time leading Goal Scorer in NCAA D1 lacrosse history
• Jeff Panzer – music video executive
• Adam Pascal – actor and singer
• Michael Pollan (1973) – writer
• Tracy Pollan – actress
• Natalie Portman – Israeli-American actress
• Felissa Rose – actress
• Liz Rosenberg – poet, novelist, children's book author
• Gabe Rotter (born 1978), novelist, television writer and producer
• Jim Rowinski – NBA player
• Dave Rubin – television personality and political commentator, host of The Rubin Report
• John C. Russell – playwright
• Carl Safina – conservationist and author
• Doug Stegmeyer – bassist in Billy Joel's band
• Brandon Taubman – baseball executive, former assistant general manager for the Houston Astros
• Doug Varone – choreographer
• Barry Weiss – Chairman of BMG Label Group
• Meg Wolitzer – novelist
• Irad Young (born 1971) – American-Israeli soccer player
• Jordan Young – television producer and writer

Syosset High was often referenced in Mort Drucker's artwork for MAD Magazine.

• Official website
• Syosset High School on Facebook