From: "Y. NOBUOKA" Date: 2011-05-12T17:53:03+09:00 Subject: Re: Where does "define_method" defined? Hi, Yes, a +define_method+ method is an instance method of the +Module+ class, as you said. However, the method is PRIVATE [1], so you can't find it by using your code. Please use following code instead. (on ruby 1.9.2-p180) Mocdule.private_instance_methods.include? :define_method => true [1] http://ruby-doc.org/core/classes/Module.html#M000497 Regards, -- NOBUOKA Yu