Even as sea-level rise, drought, and fire increase pressures on some ecological systems, others are benefitting from protection and restoration efforts. But some changes are not reversible. Long-term research employs observations of past changes, together with long-running experiments and modeling to understand the processes responsible for sustaining ecological functions. Drawing on concrete examples and new ecological theory, five researchers from across the Long-Term Ecological Research (LTER) Network describe science that can help discern which changes may allow for recovery and which are more likely to irreversibly transform ecological systems. Posters describing ongoing LTER research and samples of the LTER children’s book series will be on display throughout the morning. To attend, please RSVP to Cheryl Dybas, NSF Public Affairs (firstname.lastname@example.org), at least 24 hours in advance.