During the Mountain Phase, students receive instruction on military mountaineering tasks as well as techniques for employing a squad and platoon for continuous combat patrol operations in a mountainous environment. They further develop their ability to command and control a platoon size patrol through planning, preparing , and executing a variety of combat patrol missions. The Ranger student continues to learn how to sustain himself and his subordinates in the adverse conditions of the mountains. The rugged terrain, severe weather, hunger, mental and physical fatigue, and the emotional stress that the student encounters afford him the opportunity to gauge his own capabilities and limitations as well as that of his "Ranger Buddies". In addition to combat patrol operations, the Ranger student receives five days of training on military mountaineering. During the first three days of mountaineering (Lower) he learns about knots, belays, anchor points, rope management and the basic fundamentals of climbing and rappelling. His mountaineering training culminates with a two day exercise (Upper) at Yonah Mountain applying the skills learned during Lower Mountaineering. Each student must make all prescribed climbs to include a 200-foot night rappel at Yonah Mountain to continue in the Course. During the two FTXs, Ranger students also perform patrol missions requiring the use of their mountaineering skills.

Combat patrol missions are directed against a conventionally equipped threat force in a low intensity conflict scenario. These patrol missions are conducted both day and night over a four day squad field training exercise (FTX) and a platoon five day FTX that includes moving cross country over mountains, conducting vehicle ambushes, raiding communications/mortar sites, and conducting a river crossing or scaling a steep sloped mountain. The Ranger student reaches his objective in several ways: Cross-country movement, air assaults into small landing zones on the sides of mountains or an 8-10 mile foot march over the Tennessee Valley Divide (TVD). The stamina and commitment of the Ranger student is stressed to the maximum. At any time, he may be selected to lead tired, hungry, physically expended students to accomplish yet another combat patrol mission.

At the conclusion of the Mountain Phase, the students move by bus or parachute assault into the Third and final (Florida) Phase of Ranger training, conducted at Camp Rudder, near Eglin Air Force Base, Florida.