High school science teachers must register with the USABO. Registered teachers can then nominate any high school students. These students take the Open Exam at their high school in early February. Individuals who score in the top 10% advance to the next round. The average score on the exam is usually around 17 correct answers. In the past, a score of around 26 out of 50 has been required to advance.

USABO Semifinals:
Individuals who score in the top 10% on the Open Exam then take the Semifinal Exam at their school in mid-March. This is a 2-hour exam composed of multiple choice, short answer, and fill-in-the blank questions.

The top 20 scorers on the Semifinal Exam become National Finalists. In 2005, a student had to earn a score of 125 points out of 171 in order to advance.

USABO National Finals:
In early June, the 20 National Finalists attend a 10-day camp at George Mason University (GMU) in Fairfax, VA. The CEE and its sponsors cover all expenses for the trip including round-trip airfare, accommodations in a GMU dorm, and a generous allowance for food.

For the first 8 days, the finalists review theoretical material with professors from around the country as well as carry out experiments that hone their practical lab skills. The last 2 days involve both a theoretical exam and a practical exam. The theoretical exam is similar in format to the Semifinal Exam, consisting of multiple choice and fill-in-the-blank questions. For the practical exam, students spend approximately 10 minutes at numerous lab stations, completing a separate task at each station.

Students receive medals based on their combined exam scores. The top 4 scorers receive gold medals, the next 4 highest scorers receive silver medals, and the next 4 receive bronze medals. Therefore, 12 out of 20 finalists receive medals. The top 4 scorers (those that received gold medals at the USABO National Finals) represent the United States at the IBO.

IBO:
At the IBO, students from over 50 countries complete both practical and theoretical exams. Each country is represented by 4 team members. Although each country has a team, the members compete as individuals, attempting to receive the highest combined exam score. The top 10% of students receive gold medals, the next 20% are awarded silver medals, and the next 30% collect bronze medals.

The IBO is held annually in mid-July in a host country. Students spend several days exploring the nation and its important landmarks as well as its cuisine and cultural traditions. In 2007, the IBO will be held in Canada. In subsequent years, the competition will be hosted by India, South Korea, Kazakhstan, and Taiwan.