Governments, aiming to contain spending and reduce deficits, have transferred the delivery of many social and health services to the nonprofit sector (NPS). Since services are typically offered at no cost, nonprofit organizations (NPOs) often provide these services to marginalized populations---the homeless, those struggling with poverty, addiction and mental illness. Although most NPOs employ paid staff and volunteers they are rarely viewed as workplaces by researchers and policy makers. Little is known about the nature of work or working conditions in these organizations. A particularly glaring gap is the lack of research on occupational health and safety (OHS) issues affecting NPOs and how well current policy and practice is suited to the challenges and needs of these workplaces.This study examined the nature of work and working conditions in three NPOs providing social and health services to marginalized clients. I took an interactionist approach that recognizes meanings as context dependent and produced via social interaction. By interviewing managers and workers, and through the process of direct observation, I characterized the nature of work in these NPOs. I examined how organizational missions and the process of providing help shaped how risks were understood and managed by workers. Missions shaped how workers conceptualized risk by making visible some risks while obscuring others. Missions also seemed to have an impact on risk taking and acceptance. Sometimes workers accepted less-than-ideal working conditions or engaged in activities that could hurt them, if doing so allowed them to fulfill the mission of helping marginalized clients. In many instances workers resisted and rejected changes imposed on them that challenged the mission that was so central to their work. The function of missions in these workplaces underscores the importance of understanding the context and social production of risks in workplaces. This study also speaks to how working conditions can be improved in social service NPOs and to some of the shortcomings of mainstream OHS systems of policy and practice.