<p>20 open questions relating to sustainability are presented and discussed. It is suggested that asking, answering, and then acting upon the answers to these questions is essential to both prompt and perpetuate ‘sustainability culture’. The process is undertaken with no expectation about what answers will emerge, but rather answers emerge through examining individual and group assumptions, beliefs, and values. To contextualise the process a number of worldviews, conceptual frameworks, and theoretical distinctions are discussed. And in conclusion individual and group action is briefly considered. The questions are as follows: What is being sustained? What is not being sustained? Why is it being sustained? Why is it not being sustained? Who/what is doing the sustaining? Who/what is not doing the sustaining? For whom/what is it being sustained? For whom/what is it not being sustained? How is it being sustained? How is it not being sustained? What ought to be sustained? What ought not to be sustained? Why ought it to be sustained? Why ought it not to be sustained? Who/what ought to be doing the sustaining? Who/what ought not to be doing the sustaining? For whom/what ought it to be sustained? For whom/what ought it not to be sustained? How ought it to be sustained? How ought it not to be sustained?</p>