In this article, we consider how assessment might reinforce New Zealand curriculum goals of knowing and doing in science for active and informed participation in societies that rely on scientific knowledge to guide decision making. This focus constitutes an orientation towards "sustainable assessment". Sustainable assessment encompasses the capacities students need to learn lifelong across formal and informal settings, and alerts students to the use of their learning for societal good. Within science education, socioscientific issues (SSIs) have been found to engage students and to support the development of socioscientific reasoning. We focus on perspective-taking as an important dimension of socioscientific reasoning required to assess and operationalise the social and citizenship dimensions of an SSI. Perspective-taking acts as a bridge to the appreciation of other socioscientific reasoning domains such as complexity, inquiry, skepticism, and if and how scientific evidence might contribute to the negotiation and resolution of an SSI. We introduce and discuss two strategies that provide scenarios for students' learning and demonstration of SSIs reasoning: concept cartoons as making visible student analysis of the complexity inherent in SSIs; and concept mapping as a tool to build representations and explanations of complex SSIs. Both can support integrated formative--summative assessment of perspective-taking across different phases of SSI investigation. Importantly, these scenarios (and others) can be used to support an explicit focus on the what and how of sustainable assessment and learning for societal benefit.