Phenology is an integrative and sensitive indicator of ecosystem health and function that responds to climate, water and nutrient availability, disturbance, and environmental change. Understanding phenological responses to environmental change across spatial and temporal scales is critical for forecasting shifts in species activity and associated changes in biogeochemical cycling, landscape dynamics, and ecological processes. This session features recent advances in characterizing the spatio-temporal patterns in vegetation phenology using a variety of methods (e.g., satellite, drones, webcams, in situ measurements); determining underlying mechanistic processes; developing accurate model representations of vegetation phenology; and investigating phenological implications to key land surface processes and society.The session will also feature advancements in the field made possible by the USA National Phenology Network (USA-NPN) activities, which have provided data and tools to advance research, support decision making, and engage scientists, educators, resource managers, policy-makers, and the public in this emerging field.