What does it mean to achieve sustainability and how does use of a socio-environmental lens help move the world in that direction? In this, the theory component of the Climate in Crisis track, students will develop an understanding of socio-environmental systems, what they have in common with other complex adaptive systems and the approaches used to study them. With a focus on why a socio-environmental systems approach can help illuminate the environmental, socio-cultural, economic, and intersectional dimensions of sustainability, we will explore what different disciplines bring to this complex topic and use qualitative and quantitative approaches to grapple with problems of sustainability. How do we work with stakeholders to identify the vulnerable, the equitable paths forward, and the trade-offs? Who are the winners and losers of policy decisions? In HNUH229P, students will complement the work of this course with hands-on engagement at the level of Federal policy and legislation.