In a project, I had a need/desire to change the order that a triple state checkbox operates. I couldn't find anything inherent in Access. It normally goes: Null > True > False. I wanted it to go: Null > False > True. I was able to crack the code. It's not as intuitive as you would think, or at least that I would think. I'll attach the code in case it's useful to anyone else. I only set it up as a function so it can go into the Property Sheet since it's not returning a value. I put it in the After Update Event.