1. Make sure you are authorized to view the user’s calendar.
2. Click on Calendar's menu, then click on Preferences, then Accounts.
3. Select the account, then click on Delegation and click on the + button.
4. Type in the users name and select it from the drop down.
5. You will now see the user’s calendar under a new tab called Delegates.

For calendar entities within GT Office 365, Contacts must be synced/checked under System Preferences -> Internet Accounts -> Exchange (GTuserName@gatech.edu).  This is necessary for OS X to contact and search the Office 365 Global Address List (GAL).