Annie Stephenson joined the High Meadows Environmental Institute in September 2022 and is also affiliated with the Stockholm Resilience Center and the Potsdam Institute for Climate Impact Research. She completed her Ph.D. at Harvard University in Applied Physics. Her Ph.D. work combined experimental measurements and theoretical models to understand and tune light scattering in correlated, disordered systems for applications in structural color. Through her work with agent-based models for light scattering and data-informed model-building, she developed an interest in understanding other complex systems with large numbers of interacting components. As a postdoctoral researcher at Princeton, Annie is studying human collective behavior. In particular, she is interested in the dynamics of cooperation and conflict and collective action. In one project, in collaboration with postdoc Guillaume Falmagne, she is working to characterize patterns, including critical transitions and early warning signals of those transitions, using data from a collaborative game on the discussion website Reddit. In this same Reddit dataset, she is also investigating scaling laws in organizations using techniques borrowed from urban scaling theory, aiming to develop an understanding of why some communities can successfully mobilize individuals to reach a common goal, while others cannot. Annie and Guillaume have begun collaborating with a group of researchers at the Santa Fe Institute to further study the Reddit community structure. In another project, Annie is using social media data to understand the dynamics of fashion trends—why some spread quickly but are soon forgotten and why others can remain popular for much longer. In a project in collaboration with Professors Naomi Leonard (Princeton, Mechanical and Aerospace Engineering) and Scott Althaus (University of Illinois, Urbana-Champaign), she plans to examine data collected as part of the Social, Political, and Economic Event Database Project (SPEED) to understand the growth dynamics of social movements. Additionally, Annie attended the Complex Systems Summer School at the Santa Fe Institute, where she formed several group projects that are still active, and she has since been back to the Santa Fe Institute for two other workshops.