We are partnering with over 60 community gardens and urban farms across 10 cities to study how bees tolerate urban conditions. Multiple drivers of global change are exposing pollinators to climatic extremes with which they did not evolve. Rapid urbanization is increasing local temperatures (the “urban heat island” effect) and heat waves and droughts are becoming more intense. Many species are unable to tolerate or adapt to these rapidly changing conditions, and are threatened with declines in health. Understanding which species are most vulnerable is essential to predicting and mitigating effects of urbanization and climate change on bee diversity and pollination services.