I NEED A QUICK ANSWER TO THIS QUESTION!!

I'm on a roll!!! Finished my response envelopes, now onto the guest envelopes!!!!!

When doing the envelopes for the invitations.... do you write out the word 'and' or do you put the symbol '&'.... For example... would it be:

Mr. and Mrs. Scott Smith

or

Mr. & Mrs. Scott Smith

I think you write out and. That's what we did.