Difficult model.find

Leon, I think a left outer join of Users on Declarations would do
it.

in SQL that would be:
  SELECT * from Users left outer join Declarations ON Users.user_id =
Declarations.user_id WHERE Declarations.user_id IS NULL

in ActiveRecord, an :includes does a left outer join so (I may not get
this 100% right)
  User.find(:all, :conditions => "declarations.user_id is
NULL", :include => "declarations")

Cheers, --Kip