His first SF story appeared in Astounding in 1952. Notable early novels include Who? in 1958, The Falling Torch in 1959, and Rogue Moon, his best known book, in 1960; more recently, Michaelmas in 1977 and Hard Landing in 1983. Nonfiction includes Benchmarks: Galaxy Bookshelf (1985 -- a Locus Award winner), Writing Science Fiction and Fantasy (1990), and Outposts: Literatures of Milieux (1996).

''Science fiction is fun, but more than that, it's a compulsion. I remember to this day cracking open the Sunday funnies. I was seven years old, on vacation in Atlantic City. You've got to understand, my parents didn't allow me to read the funnies. The proprietor of the resort did not know this. She thought I was a normal kid, and she gave me the Sunday Journal-American. I opened it up, and here were all of these characters: Rick Bradford and His Time Top, Flash Gordon, and Buck Rogers, and I know there were lots of others. Some of them pretty good, some I read for years when I could get hold of a paper. But there was something immediately different about Buck Rogers, Flash Gordon, and Rick Bradford.''

''To talk about my writing is to talk about me. I decided to become a writer at the age of 9. It was all I ever really wanted to do with my life. I worked at it for 12 years before I sold anything. That's not quite true, if you stop and think that most of the stuff I wrote from when I was 18 on eventually sold.''

''One of my great joys is that I very rarely do a second draft. It's true that while the page is in the machine, I work it over, but I don't work it over very hard, and when it's done, it's done. I've never gone back and retyped a manuscript. ... Writing seems to come very easily to me. Once I get to writing, the words just sort of roll out, and it's goddam fun. And I like to think that I deal with science fiction a little bit differently from the way anybody else does. I don't write very many stories about the saving of the galaxy. I don't write very many stories with rayguns in them. I like to write fairly close to home, that one step over to the left. It isn't written for that purpose, but a lot of my stuff contains an awful lot of social commentary of one kind or another. Just because I see it, and feel like writing it down.''

''I've got 47 pages of a new novel. Incidentally, the new novel is fantasy! Well, I've had this idea for years. It's really simple: the world has a continent which is divided by a rift. The people on one side don't even know if there are any people on the other side. They can't get to it. Until finally, one of them finds a space where the rift is pretty narrow, and the emperor builds a bridge. It goes on from there. It's actually a story about the bridge. All kinds of characters come and go, and one character in particular hangs around for a long time. I can see that bridge: at the beginning, a plain, ordinary stonework span, and then people building houses on the bridge, people defending the bridge against assaults, stuff like that. Why is it fantasy? Well, some of the people are dead. My hero, so to speak, begins getting visits from the boy who died saving the world. At the moment!!, it's called 'Bridge', but it's not going to be that when it's done.''

''Science fiction and fantasy are two sides of a coin. In science fiction, people assume that everybody's perfectable. A guy takes the training or pursues the discipline, and he becomes the ruler of the galaxy. In fantasy, on the other hand, the idea is that you have to propitiate a demon or you have to somehow compel higher powers to help you this one time. In effect, science fiction is Democratic, and fantasy is Republican.''