Cross country running is a running event in which runners compete to complete a course over open or rough terrain. The courses used at these events may include grass, mud, woodlands, hills, flat ground and water. It is a popular participatory sport, and usually takes place in temperate regions during the autumn and winter when soft conditions underfoot prevail.

It is one of the sports which, along with track and field, road running, and racewalking, makes up the umbrella sport of athletics. The foremost elite competition is the IAAF World Cross Country Championships. Cross country also features as part of the modern pentathlon at the Summer Olympic Games. Cross country featured on the Olympic athletics programme between 1912 and 1924 but was dropped for following editions.

At the middle school level, cross country races are typically 3200 meters (About 2 miles). At the high school level cross country races are 5k's or about 3.11 miles. Most high school courses consist of a semi-large field for the beginning and possibly end of a race and a section of woods. The amount and difficulty of hills vary depending on the course.