Prior to the park, as we know it today, being established the Three Brothers Preserve was established in 1931 to save the alpine meadows from overgrazing by sheep. This was a 6,440 hectare area which is part of what we now know as the Sub-Alpine Meadow. The preserve was doubled in size in 1936 and the Three Brothers Wildlife Reserve was formed. Since 1941 when the Class "A" Provincial Park was established there have been several revisions to the boundaries. The most recent was in October 1999 increasing the size to 70,844 hectares.