As a member of Sandicor I thought it prudent to respond. My understanding is that if your broker belongs to a local Association, then you must join as well...and that makes perfect sense. Should you decide you do not want to join an Association you can still join Sandicor and have full MLS privleges. So that in effect makes it voluntary. Simply join an office that does not belong to an Association, pay the MLS fees and you are on your way. Sounds voluntary to me!