Stasheff's stories could be categorized as "medieval fantasy"; they are filled with sorcery, monsters, castles, etc. Stasheff has written several series of novels featuring a wizard or warlock as the main character. However, in at least the Warlock series, the "fantasy" is actually psionic or esper powers: telepathy, telekinesis, teleportation, psychometry, etc., with time-travelling enemies, and the protagonist's best friend is a high-tech computer AI in a robotic equine body.

The central theme running through all of Stasheff's novels is the spreading of democracy (constitutional republic) as a form of government. Some of his novels have a religious tinge to them.(e.g. Her Majesty's Wizard). The plot of almost every one of his novels is about a main character causing a change (whether a revolution or coup) in a society from monarchy, feudalism, or any other form of government to a more democratic and populist style of government.

Many of Stasheff's books seek to educate the reader without the reader knowing. He signals this to the reader through the character of Cholly Barman in Escape Velocity: an outlaw educator who believes that people are best taught when they don't know they're being taught. Stasheff manages to pack ideas like Hegelian dialect, mediaeval forms of government and theory of poetry into his books, more or less thinly disguised as entertainment. The Warlock Rock involves constant punning on the names of famous rock-and-roll musicians and bands, and Warlock and Son has several chapters in which the happenings reference folk songs.