Summarize the following:
You will be gathering a lot of information from a lot of people. It will be important for you to keep everything organized so that your invitations get sent to the correct parties. Create a spreadsheet that you can continue to update as you gather names, addresses, and email addresses. The following categories should be included in your spreadsheet:  Current name of the classmate Former name of the classmate (if relevant) Classmate's spouse or domestic partner Classmate's address Classmate's email address Classmate's phone number Classmate's social media contact information Most high schools maintain a detailed list of their graduates, including name changes and updated contact information. Your first step to developing a thorough invite list is to gather a list of all your class members from your school. This will likely provide the bulk of the names, email addresses, and addresses you will require. It is possible that your school's alumni office will leave off a few names for members of your class. Compare the list from the alumni office to your old yearbooks. Note any discrepancies between the two lists, and add names from the yearbook to your contact list. Facebook is a great way to keep track of former classmates as they move and change names. Set up a Facebook group early on and invite as many of your former classmates as you can find. Encourage group members to track down their friends and acquaintances from your class. Hopefully word will spread that a reunion is imminent. The Facebook group is a way to assemble an invite list as well as update class members about how the reunion planning is going. Be sure to send the group relevant updates in order to boost excitement. At this point, you might have a spotty contact list for your classmates. You might have the addresses for some classmates and nothing but a Facebook update from others. Fill in the gaps by taking the time to confirm the contact information for all your classmates. Use the information you have to get in direct touch with them: call the classmates whose phone numbers you have, email the classmates whose email addresses you have, send Facebook messages to group members, and send letters to classmates whose physical addresses you have. Ask them to confirm all of their contact information with you. You can also ask them how they prefer to be contacted and note that in your spreadsheet. After you have filled in your contact list, go ahead and have your communications team put together an email listserv for your high school class. You can use the email list to notify classmates of important reunion updates and to gather information from them as necessary. There are usually a few people who are hard to track down after graduation. They might move abroad, change their names, or lose touch with their high school friends. Create a list of these "missing classmates" whom you are unable to contact. Use the Facebook group and email listserv to ask about these missing classmates. Perhaps another classmate might know how to get in touch with them. Drum up excitement and attendance for the reunion by posting frequently to the email listserv and Facebook group. Let people know when you have settled on a venue, and let them know why they should be excited to attend. Unfortunately, sometimes high school classmates pass away over the years. If you find that one of your classmates has passed away, create an "In Memoriam" list. This will allow you and your classmates to pay the proper tribute to them during the event. Perhaps the loved ones of your dead classmates might be willing to provide you with a photograph or other memento you can use to remember them at your reunion.

Summary:
Set up a master list of class members. Talk to your high school's alumni office. Examine your yearbooks. Create a Facebook reunion group. Confirm that you have the correct contact information for everyone on the list. Create an email listserv once your contact list is complete. Hunt for missing classmates. Use your contact lists to continue promoting the event. Create an "In Memoriam" list as necessary.