Timberline High School opened its doors to 9th, 10th, 11th, and 12th graders in the fall of 1970. In the early years, the school was an open-concept school with open areas and a flexible modular schedule. The first graduating class was in June 1972. Construction was incomplete when school began its first opening day. As the gymnasium was the only building finished, 700 students met in the gym for the first week of school and gradually moved into the buildings as they were completed. After a rather chaotic first year, the school did survive, grow, and evolve. Many changes have taken place and traditions have been established.

Timberline's colors, forest green and gold, and the mascot, "Blazer," were the result of the school site. Trees, deer and other animals enhanced the environment when the school was built. The natural setting has been retained as much as possible in spite of expansion. Neighboring areas surrounding Timberline were an active logging camp toward the early 20th century.

The year 1977-78 marked the first real change from the modular schedule to a more traditional seven period day, with the open-concept retained. In 1978 the schedule was changed again to a six period day. Major changes occurred in 1980 when a $3.3 million construction project was undertaken. Many classes were housed in temporary spaces and portables until the spring of 1981 as remodeling was done, and new buildings were constructed. New construction included the language arts building, auto shop, graphics and journalism areas, weight room and wrestling addition, and the student commons. Major remodeled areas were in the gym and locker rooms, main academic building and offices. During the summer of 2000 the swimming pool was remodeled.

In 2006, voters approved funds for construction of new buildings and renovations of the gym and theater. In February 2008, phase II ended and the new building opened. This building includes three academic wings, library, commons/cafeteria, administrative offices, counseling offices and career center. In all, the new construction totaled more than 100,000 square feet and included upgrades in technology and communication systems. Phase III was completed during the 2008-2009 school year, which included the opening of the newly renovated gym, pool, auxiliary gym, theater, additional classrooms and music areas.

The school provides a desirable educational environment as well as attractive physical facilities. Students excel in academic pursuits as well as co-curricular activities. Opportunities are provided for pursuing career and educational goals and social activities.