The latest edition of the mhGAP guideline has been developed to help countries improve their capacity to address the growing challenges of mental, neurological and substance use (MNS) conditions, and reduce the treatment gap. This third iteration of the guideline includes 30 updated and 18 new recommendations, in addition to the 90 pre-existing ones. With a focus on providing high-quality, timely, transparent, and evidence-based guidance to non-specialist health workers in low and middle-income countries, these revised recommendations are designed to effectively treat and care for individuals with MNS conditions. The development of this guideline is a result of significant investment in the mhGAP programme over the past 15 years, which has enabled it to become an essential tool for improving mental health care worldwide.