This proactive conservation strategy addresses the unique situation of limber pine in the Greater Rocky Mountain National Park Area (GRMNPA). The target area includes Rocky Mountain National Park and surrounding areas of northern Colorado and southern Wyoming. The GRMNPA is at the infection front for white pine blister rust (WPBR) where populations were also impacted by the recent mountain pine beetle epidemic and are threatened by climate change. This is the first proactive conservation strategy for a five-needle pine species in North America. It focuses on timing specific monitoring efforts and interventions to sustain healthy limber pine populations and ecosystems during invasion and naturalization of WPBR, thereby putting limber pine on a trajectory that reduces the probability of ecosystem impairment in the future. The high frequency of complete resistance to WPBR in limber pine populations in the GRMNPA is a distinctive feature of this area’s ecology. Having this information and other site-based genetic and disturbance ecology information before WPBR affects the populations is also unique and warranted the development of this proactive conservation strategy. The strategy outlines recommendations to promote (1) ex situ and in situ limber pine conservation and protection, (2) increased limber pine population size and sustained genetic diversity, (3) treatments to maintain durability of genetic resistance to WPBR, (4) monitoring forest health conditions for early detection of WPBR and changes in pathogen virulence, and (5) coordinated management actions within and among agencies. The recommendations apply to the GRMNPA and possibly to all of the southern Rockies; the approach used can be applied further. The recommendations herein are expected to be relevant for at least 20 years.