Robert A. Heinlein is generally recognized as the most important American science fiction writer of the 20th century. This is the first detailed critical examination of his entire career. It is not a biography—that is being done in a two-volume work by William Patterson. Instead, this book looks at each piece of fiction (and a few pieces of sf-related nonfiction) that Heinlein wrote, chronologically by date of publication, in order to consider what each contributes to his overall accomplishment. The aim is to be fair, to look clearly at the strengths and weaknesses of the writings that have inspired generations of readers and writers.