Book excerpt: This book offers a guide to better understanding models of workplace mental health, as well as best practices for mental health professionals, employee assistance groups, employers and employees alike. The cost of depression at the workplace is staggering, both in terms of absenteeism and productivity loss while at work, and in terms of human and family suffering. Depression is highly prevalent and affects employees’ concentration, decision-making skills and memory, contributing to accidents and quality issues. Analyses indicate that the returns on investment for workplace mental health programs are significant, with employers reporting lower productivity-related financial losses and less need staff turnover due to mental health conditions. The book also addresses substance use and misuse, and ways to address such problems.