I know you already mentioned and dismissed Practical Common Lisp (free online at http://gigamonkeys.com/book/ http://gigamonkeys.com/book/), but it may be worth

I know you already mentioned and dismissed Practical Common Lisp (free online at http://gigamonkeys.com/book/ http://gigamonkeys.com/book/), but it may be worth a second look once you get a further through ANSI Common Lisp - they're pretty complementary, IMHO. You may also find the Little Schemer series helpful (though they explicitly cover Scheme, almost everything applies to Lisp) for understanding several aspects of the functional programming mindset. They're also fast reads. Dabbling in languages like OCaml, Haskell, and Erlang will also round out your understanding of functional programming. While I think SICP is fantastic, it strikes me as more of a "spend years absorbing the deeper ideas in this" book than an "introduction to the tools and idioms of the language" book. Definitely consider it once you're comfortable with Lisp, just probably not first thing.