Drexler imagines a world where the entire Library of Congress can fit on a chip the size of a sugar cube and where universal assemblers, tiny machines that can build objects atom by atom, will be used for everything from medicinal robots that help clear capillaries to environmental scrubbers that clear pollutants from the air.

In the book, Drexler proposes the gray goo scenario—one prediction of what might happen if molecular nanotechnology were used to build uncontrollable self-replicating machines.

He also promotes space advocacy, arguing that, because the universe is essentially infinite, life can escape the limits to growth defined by Earth.

Drexler's 1992 book, Nanosystems: molecular machinery, manufacturing, and computation[2] is a technical treatment of similar material.

An updated version of the book, Engines of Creation 2.0,[3] which includes more recent papers and publications, was published as a free ebook on February 8, 2007.