In 2012, the SAMHSA-funded National Suicide Prevention Lifeline (Lifeline) completed implementation of the first national Policy for Helping Callers at Imminent Risk of Suicide across its network of crisis centers. The policy sought to: (1) provide a clear definition of imminent risk; (2) reflect the state of evidence, field experience, and promising practices related to reducing imminent risk through hotline interventions; and (3) provide a uniform policy and approach that could be applied across crisis center settings. The resulting policy established three essential principles: active engagement, active rescue, and collaboration between crisis and emergency services. A sample of the research and rationale that underpinned the development of this policy is provided here. In addition, policy implementation, challenges and successes, and implications for interventions to help Lifeline callers at imminent risk of suicide are detailed.