Being a 40+ year older undergrad takes the nontraditional student to a new level. It's great, but you have to remember that most college environments are not tailored to older people (and people with dependents).
With that said, I would probably want to "pledge" as a collegiate if I were a collegiate instead of having to wait for alumnae. Whether or not that would conflict with my ADULT life and responsibilities is another issue. Many of the formalities of membership intake don't vary from collegiate to alumnae, but there are also very important things about the membership and sisterhood processes that do vary. And I definitely wouldn't participate in a lot of the social events that collegiate Sorors find entertaining.
