Pollinators form a key component of European biodiversity, and provide vital ecosystem services to crops and wild plants. There is growing evidence of declines in both wild and domesticated pollinators, and parallel declines in plants relying upon them. STEP will document the nature and extent of these declines, examine functional traits associated with particular risk, develop a Red List of some European pollinator groups, in particular bees and lay the groundwork for future pollinator monitoring programmes. We will also assess the relative importance of potential drivers of such change, including climate change, habitat loss and fragmentation, agrichemicals, pathogens, alien species, light pollution, and their interactions. We will measure the ecological and economic impacts of declining pollinator services and floral resources, including effects on wild plant populations, crop production and human nutrition. STEP will review existing and potential mitigation options, providing novel tests of their effectiveness across Europe. Our work will build upon existing datasets and models, complemented by spatially-replicated campaigns of field research to fill gaps in current knowledge. We will integrate our findings in a policy-relevant framework, creating Evidence-based Decision Support tools. We will also establish communication links to a wide range of stakeholders across Europe and beyond, including policy makers, beekeepers, farmers, academics and the general public. Taken together, our research programme will make great steps towards improving our understanding of the nature, causes, consequences and potential mitigation of declines in pollinator services at local, national, continental and global scales.