postulates...

- noun (pos-chuh-lits, -leyts)

  1. fundamental principals or prerequisites
  2. axioms or statements which are assumed or claimed to be true

what is the purpose of a post prom party?

Summit Manor Hall in Hereford, MD
Summit Manor in the Hereford, MD Fire Hall

The primary goal of a school and/or PTA and/or community sponsored post prom or after prom party has to be ensuring the safety and well-being of "invincible" high school teenagers — those who go to the prom, as well as, those who don't. Toward that end, all students who would otherwise be allowed to attend their high school prom should be strongly encouraged to attend the after prom event.
 

how do you encourage students to attend?

Well, that's sometimes easier said than done, but the experience of this parent volunteer, suggests that a couple of points need to be considered. First of all, it should be free to all eligible students. Secondly, it should offer teenagers a safe, unique, substance free, experience that would be difficult for them to plan on their own someplace else... say, at a 'friends' place where they may be unsupervised. So, do your best to make your after prom event more interesting, more inviting, more rewarding, and more memorable, than whatever a group of resourceful teenagers are likely to be able to pull-off on the same night.

Oh, and don't forget to actively promote your event at school, as well as, directly to the parents and the local business community, before students start planning their own parties. If 'all the other kids' are going to the sanctioned party after the prom, there is much less incentive — for students or 'well intentioned' parents — to spend time planning an alternative party