Actually `autoload` is in ruby core [at least as far back as 1.8.7](http://ruby-doc.org/core-1.8.7/Kernel.html#method-i-autoload), which is probably as far back as I care to look :wink:.

I believe the ActiveSupport method just overloads the Kernel method to allow you to leave off the require filename and have it be assumed by the framework, but I've been using `autoload` in non-ActiveSupport projects for a while now and always specify the filename out of habit. Also, ActiveRecord depends on ActiveSupport anyways and [uses AutoLoad](https://github.com/rails/rails/blob/master/activerecord/lib/active_record.rb#L33), so I think we're in the clear regardless.