This book is the first general book to look at the current philosophical trend known as Speculative Realism. It also compares this philosophy to the work of early-twentieth-century philosopher Alfred North Whitehead. Speculative Realism insists upon the actuality of things or objects apart from the ways that our own (human) minds relate to them and understand them; it is thus part of what has been called the Nonhuman Turn in recent thought. The book gives an explication of the main tenets of Speculative Realism, and engages in close examination of several of its main figures: most notably, Graham Harman and Quentin Meillassoux. It juxtaposes their thought to that of Whitehead, who anticipated many Speculative Realist ideas, but gives them a very different focus. In the course of this discussion, the book also touches upon other philosophical themes of contemporary concern: panpsychism (the thesis that mentality is incipient in all entities), ecological thought (increasingly necessary in this time of crisis), and aesthetics (which is presented as not merely a human concern). The book serves both as an overall introduction to Speculative Realism, for those who have not encountered it previously, and as a series of arguments within Speculative Realism. It will be of interest to an interdisciplinary academic and extra-academic audience; particularly to those in the fields of literature, continental philosophy, post-structuralist theory, art and architecture, and environmental studies.