Society faces a number of environmental challenges connected to the global and local issues of biodiversity, water, and carbon (e.g., greenhouse gases, climate change, energy development) that will require collective human action on an unprecedented scale. Responding to environmental issues will require improvements in the environmental literacy of a diverse public to make informed decisions. Environmental science literacy is the capacity to participate in and make decisions through evidence-based discussions of socio-ecological systems and is essential for responsible citizenship. Citizens take individual actions that have environmental consequences when they decide what kinds of food to buy, how they will get to work, what energy resources they use to heat their house or power their car, where they will live, and how to spend their leisure time. Citizens can also influence collective actions with environmental implications, such as land use planning, tax policies, transportation policies, or participation in international dialogs. Our collective future depends on the ability of citizens to understand and evaluate evidence-based arguments about the environmental consequences of human actions and human technologies, and to make responsible decisions based on those arguments. Preparing our nation’s students as locally active and globally aware citizens for this future makes new demands on scientific communities and on our schools and teachers. In order to be more effective, teachers need to understand more fully how students understand these concepts and thus where persistent difficulties are centered. Research on this understanding needs to include current ecological thinking and also be grounded in what is known about how people learn. This organized oral session brings together cutting-edge research by both ecologists and learning scientists on the reasoning of secondary students as they grapple with ecological concepts, such as carbon cycling, community assembly, natural selection, and water dynamics, across their formal education curriculum and how that reasoning is connected with citizenship decisions and quantitative reasoning.