[11][12] The new school began in a small building on Parsons Boulevard, originally intended as a temporary home until a permanent facility could be realized.

[13][14] Over 15,400 students compete for approximately 270 seats in the freshman class each year based on their middle school grades, standardized test scores and attendance records.

[1] Now, post-pandemic, beginning in 2022, students are grouped in tiers based on their final 7th grade core subjects (ELA, Social Studies, Math and Science) averages,[15] with Tier 1, an average greater than 94, having priority for admissions.

[17] In addition to the standard modern language requirement which may be fulfilled with classes in Spanish, French, or Japanese, students must meet a two-year classical language requirement which can be fulfilled by classes in Latin or classical Greek.

"[citation needed] In the 2022-23 school year, Townsend Harris offered the following Advanced Placement (AP) classes: Computer Science A, Computer Science Principles, English Language and Composition, English Literature and Composition, Art History, Calculus AB & BC, Statistics, Capstone, Biology, Chemistry, Environmental Science, Physics 1, French Language and Culture, Japanese Language and Culture, Spanish Language and Culture, Spanish Literature and Culture, Macroeconomics, Psychology, United States Government and Politics, United States History, World History: Modern.

[21] The curriculum and format is fairly similar to the Great Books seminars required of liberal arts freshmen at colleges around the world, with heavy emphasis on critical reading and writing.

[4] Scores on standardized examinations are also high when compared to other public high schools; in the year 2005–2006, Harrisites had average scores of 628 and 632 on the SAT verbal and math sections, respectively, compared to 551 and 565 for what the city deems "similar schools" and 444 and 467 for students citywide.