I live near Palm Beach were many schools like Deerfield, Hotchkiss, and Andover, just to name a few, are hosting admissions receptions in the homes of parents of students in their respective schools. I would like to know what one is like as my parents and I have never been to one or know anyone that has actually been to an admissions reception and what would the dress code be. I know that Deerfield said “casual dress” but I do not know if that means really casual like t-shirt and jeans or slightly more formal with a short sleeved button down and khaki shorts, or should I just go all out and wear my formal clothing. Also, I have an interview immediately beforehand for one of the receptions I will be attending so would that attire also be acceptable for the interview?
Interview attire should be fine, unless the reception really is a casual daytime event. We went to many of these in NYC and found them to be very helpful in terms of meeting Admissions staff as well as getting a feel for the school.
I would say no to a T-shirt but yes to khaki shorts and a collared shirt.
If you have an interview beforehand, just wear interview attire. Otherwise, how formal or casual tends to vary by school, as well as location. The ones held in prestigious country clubs required more formal clothing, as to fit with the club rules; the ones in hotels or more casual locations tended to be more casual in general. Deerfield wasn’t super formal for us, there were lots of people in sweaters and pants, but there are always those people that are going to show up in a full on dress or tux, just leave them be 
When my son was applying to BS, we went to a couple of these. Usually they will invite the admissions officer for your region plus a few students who also live in the area. You’ll get a chance to mingle and meet other prospies.
Be sure to have some good questions to ask. The admissions officer may or may not remember you once it comes time to admissions decisions. But it is always good to make a good impression. Make sure to fill out the name tag and display it prominently on your shirt. Wear a collared shirt and khakis.
At our local Andover event, there were approximately 100 people who attended. We saw one other family at the accepted students day program. I don’t think there was any relationship between attending the event and being accepted, but it was a good chance to talk to current students.