The National Suicide Prevention Lifeline was launched in January 2005. Lifeline, supported by a federal grant from the Substance Abuse and Mental Health Services Administration, consists of a network of more than 120 crisis centers located in communities across the country that are committed to suicide prevention. Lifeline's Certification and Training Subcommittee conducted an extensive review of research and field practices that yielded the Lifeline's Suicide Risk Assessment Standards. The authors of the current paper provide the background on the need for these standards; describe the process that produced them; summarize the research and rationale supporting the standards; review how these standard assessment principles and their subcomponents can be weighted in relation to one another so as to effectively guide crisis hotline workers in their everyday assessments of callers to Lifeline; and discuss the implementation process that will be provided by Lifeline. (Contains 2 figures.)