Seconding the recommendation for Land of Lisp. It's fun, well-written, and thorough. And has the most fun art I've seen in a programming manual. I read five gr

Seconding the recommendation for Land of Lisp. It's fun, well-written, and thorough. And has the most fun art I've seen in a programming manual. I read five great books on Common Lisp. Intro level: ANSI Common Lisp (by our very own PG), Practical Common Lisp, and Land of Lisp. Can't go wrong with any of them, but LoL has art and humor. Advanced level: On Lisp (again, PG), and Let Over Lambda (a bit rougher around the edges, opinionated, but full of clever programming tricks).