We visited this site for ideas for my son's Harry Potter Birthday party and he insisted that I share our party ideas after it was all over.  Invitations:  We did a google images" search for "Hogwarts" and got the logo.  Then I inserted it into a word document as the cover of the invitation. We went to the first Harry Potter book for the language inviting Harry to Hogwarts and slightly modified it to fit with the party.  We told them that RSVP could be by Owl Ravenclaw and Hogwarts.  We printed them and hung them at the entrance to our house. We used gold and crimson balloons ribbon table cloth and streamers.  We also got plastic wine glasses (goblets) and cauldron's to serve drinks.  Activities: The idea of the party was that the kids would be divided into two houses and compete for the house cup. When they arrived they waited in the living room.  As soon as they all arrived Professor McGonical (my mom in a witch had and black skirt) explained the plan. Each child was given a list of items they needed to purchase from Diagon alley (our upstairs). First Gringots to get there wizard money next the Olivanders for a wand (we used sticks soaked them to get the bark off rounded the ends and wrapped the handle end in electrical tape) then to the apothacary for their cauldron (I used brown paper gift bags but cut out cauldron shapes out of black paper and pasted them to each side)  and beans (explained later) finally to Flurish and Blotts for their "books" (Harry Potter Word Find).    When the kids came down stairs we quickly opened presents to get it out of the way. Then we moved on to the Sorting hat. We explained that they would be divided into either Gryffindor or Ravenclaw and would compete in games for the house cup.  I made the sorting hat out of a paper bag.  Professor McGonigal would call a child's name and hold the hat (also holding a walkie talkie inside) over the child's head. My husband hid in the other room to be the voice of the hat. The kids loved it! As they were sorted we gave them a T-shirt of their house. It had the house crest on the front and the movie poster image from Harry Potter and the Sorcerer's Stone on the back with my son's face instead of Harry.  I used Microsoft publisher and t-shirt transfers to make the shirts.  Games: After being sorted we started the games. First the word find. I found an easy program on-line that creates wordfinds using whatever words you specify. They did this as a team and had 10 minutes.  Next the guess the flavor of the every flavor bean game. I bought jelly belly's in advance identified 10 specific flavors then made bags for each child with one of each flavor of bean. Each Team had an adult helping who had a extra bag of beans and an answer key with blank lines to tape the guesses too.  The kids decided as a group which bean was which flavor.  Next was a broom ride relay race followed by the dementor pinata.  I made the pinata out of a punch balloon newspaper with flour paste black spray paint and black fabric.    At the end of each game my husband in a dumbledor hat would award points.  After eating cake he announced that the final score was a tie due to the valor of the trailing house and every kid got a medal to wear.  Costumes: I had several witches hats for helpers a black skirt for Professor McGonical a hat for Dumbledor a crazy wig for Olivander and a black Robe for the birthday boy. Cake etc:  Because we have a big group I made "wizard cupcakes" cupcakes with chocolate icing a sugar cone on top and orange icing around the cone.  My sister also made a flying snitch cake and we had gold candles.  We also had orange soda aka pumpkin juice.   Favors:  The favors were easy because they were all a part of the theme. Each kid went home with a wand a t-shirt and candy from the pinata.    A good time was had by all :) "