People with mental health conditions have been excluded from the development agenda despite being a marginalized and vulnerable group in countries all over the world. This report highlights the urgent need to redress this situation. It presents compelling evidence that people with mental health conditions meet major criteria for vulnerability and yet fall through the cracks of development aid and government attention. It makes the case for reaching out to this vulnerable group through the design and implementation of appropriate policies and programs and through the inclusion of mental health interventions into broader poverty reduction and development strategies. It also describes a number of key interventions which can provide a starting point for these efforts. This report is a call to action to all development stakeholders, multilateral agencies, bilateral agencies, global partnerships, private foundations, academic and research institutions, governments and civil society to focus their attention on mental health. By investing in people with mental health conditions, development outcomes can be improved.