To moderate associations use:

has_moderated_association :links, :comments

to moderate the links and comments associations. You can use :all to moderate all associations, but I recommend you explicitly specify them.

Be especially careful if you are moderating a has_many :through association. In this case, you must moderate both associations. For example:

has_many :bookshelves
has_many :books, :through => :bookshelves
has_moderated_association :bookshelves, :books