With the unprecedented increase in humanitarian emergencies in recent years, growing numbers of people are facing adverse living conditions and are at risk of developing mental health problems. The defining feature of this manual – which was developed to help one individual at a time - is that it was designed to support adults impaired by distress, regardless of the specific mental health problem they are experiencing. This means that more people can be helped through a single brief psychosocial intervention. Secondly, it comprises evidence-based strategies adapted so that they can be delivered by supervised non-specialist providers after brief training. This is critical if we want to bridge the gap between mental health problems and access to effective care. In many settings where mental distress is high due to adversity there is a lack of psychosocial support, including a lack of mental health professionals. Group PM+ is designed for adults impaired by psychological distress and can be delivered by non-specialist professionals following brief training and with ongoing supervision. It draws on the same therapeutic strategies as the individual version of PM+ and is delivered over five two-hour sessions. The effectiveness and feasibility of Group PM+ has been shown through randomized controlled trials conducted in Pakistan and Nepal. With this manual, and following cultural adaptation, governments and civil society will be better equipped to respond to and manage common mental health problems for adults affected by adversity.