The following were the qualification criteria for the 2024 IESO. Qualification for the next IESO will likely work differently. It will be announced once the next date for IESO has been determined.
Students qualified for the 2024 International Environmental Science Olympiad in a number of ways:

01.

Students in the USA may qualify for the International Environmental Science Olympiad by taking the International Environmental Science Olympiad Qualifying Exam. Students must score 75 or higher if they take the exam while in 9th-12th grade, 65 or higher if they take the exam while in 7th or 8th grade, 55 or higher if they take the exam while in 2nd-6th grade.

02.

For students in the USA, any student who qualified for the National Championships of the National Science Bee in the 2022-23, 2023-24, or 2024-25 academic years qualifies.

03.

Students in the USA can also qualify by scoring 75 or higher on any version of the National Science Bee National Qualifying Exam while in 9th-12th grade, 65 or higher on any version of this exam if they take the exam while in 7th or 8th grade, or 55 or higher on any version of the exam if they take it while in 2nd-6th grade.

04.

Students outside the USA qualify if they score 60 or higher on the International Environmental Olympiad Qualifying Exam while in high school equivalent, 50 or higher if in 7th grade or 8th grade equivalent, or 40 or higher in 5th or 6th grade equivalent, and 30 or higher if in 2nd-4th grade equivalent. Grade equivalents for the 2024-25 academic year: 9th-12th grade: born 31 August, 2010 or earlier, 7th-8th grade: born 1 September, 2010 to 31 August, 2012, 5th-6th grade: born 1 September, 2012 to 31 August, 2014, 4th grade and younger: born 1 September, 2014 or later

05.

Students outside the USA also qualify if they qualify for the Canadian Championships, European Championships, or Asian Championships of the International Science Bee during the 2022-23, 2023-24, or 2024-25 academic years. They can do this through the Championships Qualifying Exams or through a regional quiz tournament.

06.

Students can also qualify for IESO by finishing in the top 2/3 of students in their age division who took the National Environmental Science Exam at the IAC US National Championships in the 2022, 2023, or 2024 academic years.
Students can also qualify for IESO by finishing in the top 2/3 of students in their age division who took the Environmental Science Exam at the IAC Asian Championships or IAC European Championships in the 2023 or 2024 academic years.

Note 1: Students must be in 3rd grade-12th grade during the 2024-25 academic year to attend IESO.

Note 2: Students in Canada do not use the grade equivalents as listed here, but rather their actual grades just as students in the USA do.

Note 3: A list of students who have taken the International Environmental Science Olympiad Qualifying Exam is maintained here.