When my son turned 7 he wanted a Harry Potter party! His birthday came right after the 4th movie came out, so they had lots of new stuff and all the kids were really into Harry mode again.  Invitations-  I got some "parchment" stationary and typed up the invite to be just like the Hogwarts letter of acceptance. Obviously I changed the wording a bit- "You have been accepted.... Please come dressed as a wizard or your favorite character... Please bring a broomstick to start your quidditch training... we will begin our start of term feast with Josephs 7th birthday celebration... arrive at platform 9 3/4 at 3:00... please respond by owl or muggle phone. I hand delivered all of them and had the Moms leave them on their beds. Almost all of the kids were ecstatic and kept asking my son where he got his owl! And every one of them did dress up, so we had 3 quidditch players, 2 Hogwarts students, 1 deatheater, and Ron, right down to the red hair and freckles! As well as all our family and friends who we told to either dress up or dress with something Irish (in support of the Irish National Quidditch team). All of us really stuck out going to see the movie after the party was over!  Decorations-  My friend and I made a Platform 9 3/4 by getting some maroon butcher paper and painting black vertical and horizontal lines. Then we took some white chalk and lightly colored in only some of the bricks. We cut it to fit our front door. Then I got a white poster board, cut it in half, and painted a 9 and 10 on each one. It looked great! My son had the idea of having spiders crawling along our front entrance. So, I pulled out all the spiders from our Halloween spider webs and taped them going in a line on the wall leading to our Platform. We have a great room (living room/dining area) so for that room I made it like the great dining hall. I have those star wire garlands for our Christmas tree. I pulled those out and strung them all over the ceiling. It looked good, but better if we had more. I also put on a DVD with the TV off and kept it on the menu so the Harry Potter music kept playing throughout the party.  Activities- Quidditch training- I made goals out of things in our garage (metal stakes, rubber netting). I just tied it together and put them at either side of our yard. The invitations told the kids to bring brooms, but we had family bring some just in case (we used all the spares). I split them up into teams (it was uneven, but it really didn't matter) and they had to hit the soccer ball with their brooms into the goal. Pretty simple. We did have to stop several times for fallen players and kids who forgot to keep their brooms vertical. But, they seemed to have fun. Photo op- take a shot of all the kids together with their brooms. I told them all to look mean. It came out great! Potions class- My husband was able to get those beaker and test tube sets from his schools science lab. That really made it look good. We had it all set up in the kitchen. He is into magic, so he found a few potion related magic tricks to perform. We had pre-poured all the ingredients he would need into the various jars and labeled them differently (ash of phoenix, thestral tears, ghost oil, powdered dragon fang). As well as random beakers with gross things such as eyeballs in them. 1st was a disappearing potion, that, oops, disappeared! Kids thought that was funny. Then was a gold potion. He put all the ingredients in a pan, had the kids write on paper what they would do with lots of gold, put that in the pan, set it on fire (to melt the gold), put the fire out with the lid and when he lifted it up, there were gold coins for the kids (trick pan). Last was a naughty and nice potion. He put in sugar, spice, and a jar labeled everything nice. He poured it all in a bag and it started to shake. Something was obviously wrong. He told the kids to check the jars again and they found the nice jar had a label underneath. It said everything not nice. He reached in the bag and out popped a SCARY bunny! But, the sugar and spice part worked because there was candy inside as well. Taste testing- We had 3 jars and 1 vial for the kids to try. They were labeled troll snot (honey and green food coloring), bat blood (kool-aid mix and water, no sugar), goblin pee (lemon juice and water, no sugar), and crushed dragon heart (crushed fireball). Quill making- I bought those neon gel pens, feathers, metallic pipe cleaners, and a sheet of small gold star stickers. I demonstrated how to wrap the pipe cleaner around the feathers at the bottom of the pens. This did not take long at all. Immobulus- We went back outside for a magical version of freeze dance, though I didn't have any music. Probably would have been more fun for the kids to have music. Basically, the kids dance and one kid, armed with wand, shouts immobulus. Whoever is moving grabs the wand and is the next "it". That got some energy out while dinner was being picked up.  Food-  I had some ideas for "gross" food but just thought it was easier to do pizza. So we did that and had Potter potion to drink (ginger ale and sherbet). It foams, so does kind of look like potion. Grandma made the cake. Did sparkly blue crystals to look like sky. Made a scroll that said Happy 7th birthday Joseph and stuck it in upright with a straw. Got mini brooms and stuck them upright in a circle the tops of which held up the snitch. The snitch- foil ball, fasteners, and mini feathers all spray painted gold. I think she got everything at craft store. I got the idea of having sparkler candles that don't go out. It was a hit! The kids were laughing hysterically and all helping my son try to blow them out! Gifts- To try to control the mania of gift opening time, I had each kid grab the gift they brought and sat them in a circle. When my son saw the one who was sitting the quietest, he would say, "Accio kids name" and they would give the gift. Worked pretty well.  Goody bags-  At the party store I picked up Harry glasses, broom keychains, "Gringotts" gold (same as used in potion class), and "Mad-eye Moodys" eye (ping pong ball eyes I got during Halloween). Rolled up several sheets of copy paper and tied it with rafia for scrolls. Got lightning bolt tattoos at the Barnes and Noble book party. Asked manager where he got them or if I could but some from him and he gave me about 100 free! It pays to inquire! And they also had their quills they made. I thought about attaching some kind of band to the eye to make it wearable, but never got that far.  I would like to point out that you should definitely have extra activities in mind. I allotted 2 1/2 hours for the party and even with all the stuff we had going, the kids were flying through things so fast that we were eating cake and had 35 minutes still. During pizza I played Harry Potter trivia with them (just pulled things out of my memory) which they liked and started thinking of trivia themselves. After cake I got out the bertie bott beans and gave some to all the kids. That filled in some time and they enjoyed that, even if they got yucky flavors. Last but not least, at some point during eating time, the doorbell rang and someone said my son had something at the door. There was an all Harry Potter magazine wrapped in scroll with his name on it with a feather inside. The kids were convinced an owl brought it! I think it was my Father-in-law, but nobodys talking!