ISEF is different from the other listings here: there’s no single application you submit directly. Instead, you enter your school’s or region’s affiliated science fair, and top projects from each fair earn a spot to compete at ISEF itself. Over 1,600 students from 60+ countries and regions compete each year for close to $9 million combined in awards, scholarships, and prizes.
How to actually get started: ask your science teacher or school counselor in the fall whether your school participates in an ISEF-affiliated fair (most regions have one), since the qualifying rounds happen well before the ISEF event itself. Physics is one of the official competition categories.
Regeneron ISEF 2027 will be held May 8–14, 2027, in Los Angeles.