When my daughter Gabriella was turning 1 it was not a problem deciding what the party theme would be. Of course her favorite character ELMO. For invitations we sent out the store bought Elmo Invites (from PartyCity).  The party decorations were all based on the primary colors. At the cake table was an Elmo table cover, and the same at the gift table.  At the seating tables were blue and red table covers. We had red, yellow and blue plates - which we collated for variety. The forks, spoon, knives, were all red, yellow and green, cups were blue and yellow. We used Elmo cake plates and Elmo cake napkins, but for meal napkins used blue and green. All those items were found at PartyCity for $.99 each or less - except for the Elmo print supplies, which were a bit more. I made a SESAME STREET sign out of thick yellow poster board (foam board)that I cut into the shape of the actual sign from seasame street. I then cut regular green poster board in the same shape, but 1 1/2 inches smaller and added white letters that I cut out with stencils that said SESAME STREET - and had the numbers 123 on the top. It was so cute - everyone wanted to know where I bought it!!!  It could easily be attached to a carpet tube (cut in half - lengthwise and painted green) that is put into a plastic stump style x-mas tree stand.  It will look identical to the actual sign from TV.  I also made a sign that I painted with primary colors that said This Party Is Brought To You By The Letter G And The Number 1"  I printed out an Elmo picture then cut him out and attached him to the back of the sign as if he was peeking out of the side holding the sign.  Of course the room(s) were covered in red yellow blue and green balloons and streamers. Our food was based on my daughters favorites (chicken teryaki w/rice mixed seasoned vegetable baked beans meatballs and sauce and macaroni salad - all homemade).  It was also a mid-afternoon party so we felt we needed to really feed our guest (rather than just give finger foods). We did have Goldfish for snacking on and for the cake it was an Elmo sheet cake from our local grocers with the Elmo characters on it (Dorothy Elmo Mr. Noodle) - we also had them decorate the frosting accents with primary colors and put frosting balloons on it. Since it was our daughters first birthday they also included a free 8" round cake for her that was decorated in the primary colors with balloons also. We gave this to my daughter to enjoy on her own. She dug right in and we have beautiful pictures of this to share with her later - frosting from head to toe - and to send to all our guest as a thank you note.  For games we played pin the nose on Elmo - from an Elmo poster that I made. We colored the pictures I downloaded and printed from the SS website the letter G - which had Oscar the Grouch on it and the number 1 from their site which had Elmo on it. They have all the letters and numbers on their site - so all names and ages can be accomodated. We played a balloon game where kids had to team up and hold a balloon between two of them at their tummy and work together to get across the line first with out popping or dropping their balloon. Kids loved that. Our center piece was a real goldfish that we gave to the birthday girl as a gift (she is a huge fish lover - stares at our tank all day long). We also had an Elmo pinata.  I was a bit leary about this at first not wanting kids to be smashing at my daughters favorite character. But I found a pinata that had pull strings at the bottom. Each child had a turn to pull a string and see if they could open the secret door for the prizes inside. I am not sure if it is made to work so that the last string is the one that opens it but that is how it worked with us - which was great because it gave each child a turn to pull a string. The loot from the pinata was placed in Elmo goodie bags that we pre-printed each childs name on.  For goodie bags we did Elmo themed bags bought at PartyCity and filled them with and Elmo plastic cup (also PartyCity) a full size tub of Play-Doh(WalMart 4/1.90 or so - much bigger than the "party size" and in a quantity that kids can actually play with) Elmo stickers(PartyCity) Elmo bouncy balls(PartyCity) Bubbles(WalMart - 6 pack for $1.88 in the toy section) we also added a MatchBox for the boy bags and a hair accessory for the girl bags.  Amazingly all this fit into the bag (this is the larger of the bags that PartyCity had).  This party was for about 13 children and 16 adults. Thankfully our church let us hold it in one of their larger rooms (which was great with their large kitchen to warm and prep stuff not already made). The party was about $150 including all food cake decorations and accessories. I thought that was pretty good for 29 (33 including us) people."