Hi Stephanie,
Check to see if this family has visibility permissions under visibility graphics. Type command "VV" to bring up the 'Visibility/ Graphics Overide' window. Check the family's model category is checked, then apply and close. If it's already checked, you may need to open the Revit Family and check that the element has this 3D view display option turned on. To check this, open the family in Revit and select the model (or the element of the model) that you want to see in the 3D View. With the element selected, click the "visibility settings" under the 'Modify' Ribbon and a pop up window, "Family Element Visibility Settings" will open. Check any boxes that are unchecked under "View Specific Display" and close the window. Select "Load into Project", go to the 3D view and the model should be visible.