I have a lot of thoughts about this so bear with me here. First and foremost, you're not too old for a birthday party, EVER. Second of all, this should be all about you and your likes, and your happiness. Any reasonable adult can manage mingling and making new acquaintances at a party on their own. You shouldn't be worried about that. If someone chooses to sit in the corner, that is their problem, not yours! Also, some people might be more comfortable that way. That doesn't mean you did something wrong. It's not your job as the birthday girl to micromanage everyone else's social mobility. I would suggest telling your closest/best friend(s) that you want to throw yourself a birthday party and ask if they would be interested in helping you. When I say closest I mean like 1 or 2 people. That way, there is someone who can help you set up and be the person to bring out cake, and be like a secondary hostess in addition to yourself. Let's go through your questions. How long should the party be, when do people sing, when to do cake: are a majority of your friends parents, or people who like to turn in early? if so, a nice dinner party that is from around 5pm to 9ish or so might be nice. if you have a little bit more of a party crowd, go for a 7pm-whenever party. you don't really need to specify an end time unless you're concerned about people overstaying their welcome.   How do I get more comfortable with bringing people together who don't know each other?: again, it is part of being invited to a party that you have to mingle with your friends' friends. you should not have to worry about this. try not to take on the responsibility yourself. What activities can I do: what would you enjoy? what is fun for you? you could have a more upscale dinner party with a few bottles of good wine and some fancy cheeses and fruits and bring out a game that encourages people to have conversation with one another. better yet, a game where people have to get on teams to play. if you and your friends are a silly/rowdy bunch you could serve beers and seltzers and find a karaoke machine. you could also put on a good movie on the tv, play some nice music from a stereo, and have things like dice and playing cards around so that people can naturally fall into their own activities. I think your notion that people just sitting around talking doesn't make a good party is false. it's totally okay not to provide everyone with special activities. you're adults! they should be there to enjoy your company and have a nice time. Do you decorate for a party you're throwing for yourself?: This is where a close friend comes in. Enlist some help from someone who cares about you. for a dinner party you could put down a nice table cloth and buy some fresh flowers and light a few candles. for anything else you could throw up a banner that says "happy birthday" and just make sure your house is clean. believe it or not, a party playlist sets the ambience more than decorations ever will.   How much food do I need?: You definitely need cake if you like cake, that part is for you! Other than that, you can have anything from a full dinner to "party snacks" to just some pretzels, nuts, and candy. Just be transparent about what food will be there so people can plan accordingly. I recently went to an adult birthday that served popcorn, jelly beans, and tequila. If you don't want to make cocktails, provide wine and beer. Alternatively, pick two hard liquors and a couple of mixers. i.e. whiskey and cokes/gin and tonic. vodka and juice/tequila and marg mix. people can make their own drinks :) dont forget ice! What invitation method are people using nowadays?: text message or good old fashioned paper invites. although I would say a paper invite does kind of imply a more "serious" party like a dinner party. Do I need a theme? Do you think a themed party is easier or harder to execute?: You don't need a theme. The point of a theme is to just add fun to the party. It's harder if you're going to stress over it. It's fun if you think it would be fun to dress up as \_\_\_\_, and you're excited to do so. Do I bail on the idea of a home party and just invite people to a restaurant instead: I think home parties are lovely and much better than gathering people who aren't all acquainted at a restaraunt.   Overall, remember that this is your birthday and your main focus should be celebrating yourself and fulfilling your own desires. It's everyone else's responsibility to gather around and celebrate you, and refrain from stressing you out or making your life more difficult! I hope you are able to have a party that you enjoy and don't forget to take photos for years to come.