Is Lisp object oriented? CLOS is excellent and highly object oriented. Is Smalltalk a functional Language? ST has functional features like the ability to pass a closure but is not a canonically functional language like Haskell for example. Then again CL is not a Canonically functional language either despite it also having functional features, even more so than ST. CL is a multi paradigm language: some functional, OO with CLOS. ST is almost entirely OO with a taste of Functional. It's more of a question of degree. Program in them yourself and be the judge. My opinion only: Both are the best two OO languages but as functional programming goes are "ok". if you really want to go functional, go Haskell. I've actively coded in all three through the years. Haskell's function features and semantics are "functional programming done right" while ST and CL/CLOS are OO done right.