(Excuse the spelling, I am in a rush) For my son's 7th birthday party (in Oct., ususally bad weather but this year we got lucky) I went one day after school & handed out scroll invitations that were addressed to the person in the cupboard under the stairs letting them know that Madam Magda...(the head professor lady) had invited them to Hogwarts and they were to dress in their best wizards attire.  I had 30 children show up and as they arrived in the front yard they were given a cauldron and a treasure hunt list of things to find in the lawn such as snakes, frogs, lizards, and a red stone (the Scorceror's Stone) and some candy (various kinds), these were their potion ingredients. The snakes & lizards expanded in water...very cool. Once a few of each of the items on your treasure hunt list you were allowed to walk thru the wall & onto the platform (a large brick wall of cardboard that replaced the front door and had a panel that moved when you walked thru it.  Once inside you had to walk along a trail that lead to the basement.  As you went down the stairs into the basement the ceiling was full of gold balloons and and a huge crest of the Hogwarts symbol was hanging (thank goodness for ebay having the original crests on felt). In the basement each of the children were given a piece of black fabric & 3-D markers to make a wizards cape. Once the capes were done & taken upstairs to dry we pulled out the sorting hat (again...ebay).  The big room of the basement was designed to create the dining hall of Hogwarts. I painted butcher paper gold with glitter & hung it over all the walls, hung netted Christmas lights from the ceiling to recreate the floating candles & had 4 eight foot long tables, one for each house, covered in the house colors. Along with the crest of each house above each table. Along with floating golden snitches (painted styrafoam balls with feathers)  We put a walkie talkie in the heat vent & my mom stayed upstairs & was the voice that sorted them into their houses. Then we played a Hogwarts trivia game & each house got points for correct answers.  Then they were each given their wands which were wooden dowels painted black with the tip the color of their house so they knew who their team makes were (they took these home with their cauldron & potion ingredients). We went outside, played wizard games that used the swords & each team was each house. I also made a pinata of the golden snitch (gold round circle with painted cardboard wings).  Then we had cake & ice cream. When each child left they in their cauldron a Thank you card, chocolate frogs (I ordered the molds & just melted the chocolate), Berttie Bott Beans, and some HP Trading Cards & stickers.  All the kids had a blast & this year I need to create my house into a castle & he wants all the boys to be knights & princes & all the girls to be princess & maidens.....  The HP party took me 2 months to plan for & prepare for but it was worth it!!!  This site was a huge help! Thanks for all the ideas!