Just make sure your objects deserve to exists as objects. Is the Person class needed for inheritance? Does another class use Persons outside of Groups (and would a group of one be a problem)? You may find that when you start absorbing or duplicating functionality from one class (Person) into another (Group), the original class becomes nothing more than a glorified hash. It's good to keep a sense of perspective (and humor) about objects - my favorite thing about Perl is the "bless" keyword...