Because Lessing set some of her novels in a futuristic setting, it's fair to say she wrote "science fiction." A friend called these books "dystopian novels," to which I replied that dystopian novels are, in fact, a type of science fiction. Unlike Margaret Atwood, who tends to put down our genre, I never heard Lessing reject the label. As someone who believes genre means a form of literature and not a synonym for crap, I see this as a good thing for spec fic fans.
Yeah, Doris Lessing!