Our knowledge and awareness of mental health has never been greater.Yet little progress has been made in addressing a key cause of population mental ill-health: financial insecurity. This book argues that tackling inequalities through the social security system could offer a new focus to help stop our current trajectory of worsening poverty and distress. Featuring original research and focusing on three key areas: prevention, support and investment, it sets out how well-designed social security systems could play a central role in our collective mental health and discusses the changes that are needed to get there.