A 50th high school reunion is a great time to celebrate what high school meant to you and your life now. Invite as many of your former classmates as you are able to contact, and have plenty of activities planned to break the ice. Keep guests entertained and encourage reminiscing.
Plan to decorate the venue where your reunion will take place before the guests arrive to create a fun atmosphere. If your reunion is not taking place in your former high school, decorate the venue with school memorabilia from your graduating year, if possible. Or, pick up streamers, banners, paper plates, and other decorations from a party supply store that proudly exclaim "50."
When you're deciding on centerpieces for the tables, think about an interactive one. You could set up a time capsule (which could be any kind of container) and trinkets from high school, such as photocopies of yearbook photos or sports team uniforms, and encourage guests to put together time capsules at their tables during the reunion.
Guests may need the help of name tags to recall their classmates, but you could go an extra mile. Use printable name tags to print out each guest's senior picture next to his name on the name tag. This way, if names have changed or guests don't quite recognize a name, faces will be easier to recall.
If you're having music at your reunion, talk with the D.J. beforehand and ask her to play hits from the year you graduated. Look at Top 40 charts from each month of your senior year and pick out plenty of songs that will take your guests back to the good old days.
In addition to a welcoming message or toasts, it might be fun to allow some of the classmates to make speeches to the entire crowd. If your school did "the ideal classmate" your senior year and named who was best looking, most popular, etc., allow those people to share with the group. Have them give a speech stating what their title meant to them their senior year, and if that title has anything to do with what they've done with their lives.
If your class didn't do "the ideal classmate," you could have the valedictorian or class president speak, or simply have an open mic session where people can share fun high school memories.
If you have a D.J. or an emcee, you can play class trivia. Offer prizes, or dismiss tables to the buffet lines when questions are correctly answered. Keep trivia questions specific to your school and your class. You could ask questions like, "how many times has our basketball team made it to nationals?" or, "What was the last dance song at our senior prom?"
If you want to make a very large time capsule, or have guests participate in making a display for the reunion, you could visit a thrift store prior to the reunion and purchase items from your class year, such as knickknacks, clothes, or popular records. Pile them in the venue, and have guests work together to compile them into a display or time capsule. This is a great way to get guests reminiscing about what life was like the year they graduated. Take plenty of pictures.
One of the simplest ways to get guests involved in the reunion is to place disposable cameras on each table and encourage everyone to take lots of candid photos throughout the reunion. After the reunion, get the pictures developed and send copies of photos to the people who are in them.