As the former orchard lands of the west side were converted into subdivisions (in particular, "Lakeview Heights") subsequent to the construction of Okanagan Lake Floating Bridge (1955) linking the west side to Kelowna by car, a growing population of students was required to travel either to Westbank, or to Kelowna Secondary School downtown.

MBSS opened in 1975 and relieved the crowding at George Pringle in particular, where from 1973 classes had been divided into two "shifts" to accommodate overflow.

They included a trades or "shops" building with woodwork, metal work, automotive mechanics, and drafting rooms; a gymnasium with a mezzanine for weights and mat training and rock climbing; a multipurpose room with a stage which opened either to the interior of the multipurpose room or to an open-air amphitheatre, a music room adjoining the gym; and a two-storey academic building containing liberal arts and humanities classrooms, library and administration on the upper floor and science laboratories on the lower.

However, even in the mid to late 1970s there were notable achievements which ranked the school near the top of the local or provincial heap in several areas.

These included the volleyball program, which was consistently competitive at a provincial level (under the guidance of Barry Kingsley), and the debating program (organized by Colin Castle) which produced top-level debaters from the school's beginnings.