Over the last half-century, the world’s human population has doubled, impacting almost all ocean and land areas. The threats facing primates in the wild have never been greater or more complex. Primatologists have long been aware of these threats and, since the 1970s, have coordinated efforts to safeguard these threatened species, through the International Union for Conservation of Nature Species Survival Commission (IUCN SSC) Primate Specialist Group (PSG). In an effort to stem the threat of extinction to primates, this group of now 700 experts+ has published 17 conservation action plans since 1977. As we look toward the next half-century, we take stock of the history of primate action planning to better understand the costs and benefits of these plans as a conservation tool. Here, we reviewed all plans published by the IUCN SSC PSG. In total, they described USD 246 million in planned primate conservation programming and were cited 1,657 times by others. We found that half of the plans had been assessed in regard to their implementation, although these assessments were not standardized. Those that had been assessed, showed evidence of positive impacts on awareness raising, collaboration, fundraising, project implementation and policy, although the impact varied by plan. For example, three of the plans directly resulted in USD 15.92 million in funds raised; four plans quantified implementation rates, which ranged from 38% to 74% of actions partially or completely achieved 5 years after plan publication; and four plans attributed the gazettement of 19 protected areas across 11 countries as indirect successes following the publication of plans. Considered together, we reflect on the ‘return-on-investment’ for developing these plans and consider a range of ‘lessons learned’ for future primate action planning efforts.