Humanity confronts a daunting double challenge in the twenty-first century: meeting widely-held aspirations for equitable human development while preserving the biophysical integrity of Earth systems. Extant scientific attempts to quantify futures that address these sustainability challenges are often not comprehensive across environmental and social drivers of global change, or rely on quantification methods that largely exclude deep social, cultural, economic, and technological shifts, leading to a constrained set of possibilities. This article combines three previously separate streams of inquiry—scenario analysis, planetary boundaries, and targets for human development—to show that there are plausible, diverse scenarios that remain within Earth’s safe bio-physical operating space and achieve a variety of development targets. However, dramatic social and technological changes are required to avert the social-ecological risks of a conventional development trajectory.