The United States and other contemporary societies face unprecedented environmental challenges as a result of climate change and escalating urbanization, ranging from acute hazards (e.g., natural disasters) to chronic, slow-onset stressors (e.g., prolonged drought, rising urban pollution levels, intransigent urban spatial inequities). These challenges threaten human health and well-being; destabilize assets, coping capacities, and response infrastructures; and substantially increase the number of socially, economically, and psychologically vulnerable individuals and communities. They disproportionately affect populations of lower economic privilege or social status, disrupting employment and income, escalating food insecurity, and degrading the ecologically vulnerable, inadequately resourced locations where poor and marginalized groups often live. Environmental inequities are also social inequities, with significant social justice implications. Social work is positioned to play a key role in developing and implementing innovative strategies to anticipate, mitigate, and respond to the social and human dimensions of environmental challenges. Core areas for social work leadership include (1) local, national, and international disaster preparedness and response; (2) assistance to dislocated populations; (3) collaborative capacity building to mobilize and strengthen place-based, community-level resilience, assets, and action; and (4) advocacy to elevate public and policy attention to the social and human dimensions of environmental change.