Public variables will certainly work, but are a poor programming practice, as you will have no control over values assigned to the variable, nor will you know when a value is assigned. I NEVER use public variables for these reasons. Add a new Property to the form to pass values. This will allow you to validate the incoming value, as well as execute other code inside the form when a new value is passed. Trust me, as your program grows and becomes more complex, little things like this become more important. Program defensively!