It seems intuitively clear that not all human endeavours warrant equal concern over the extent of their sustainability. This raises the question about what criteria might best serve for their prioritisation. We refute, on empirical and theoretical grounds, the counterclaim that sustainability should be of no concern regardless of the circumstances. Human security can serve as a source of criteria that are both widely shared and can be assessed in a reasonably objective manner. Using established classifications, we explore how four forms of sustainability (environmental, economic, social, and cultural) relate to the four pillars of human security (environmental, economic, sociopolitical, and health-related). Our findings, based on probable correlations, suggest that the criteria of human security allow for a reliable discrimination between relatively trivial incidences of unsustainable behavior and those that warrant widely shared serious concern. They also confirm that certain sources of human insecurity, such as poverty or violent conflict, tend to perpetuate unsustainable behavior, a useful consideration for the design of development initiatives. Considering that human security enjoys wide and increasing political support among the international community, it is to be hoped that by publicizing the close correlation between human security and sustainability greater attention will be paid to the latter and to its careful definition.