accessing an arraylist from another form

I'm enjoying C#, but every now and then I come up against a brick wall. My problem is that I have a class with an arraylist that is populatd from a text file on my HD. On a form I have a listbox that needs to be populated with items from the arraylist, but I am unsure as how to go about accessing the arraylist from another form. Any help woud be great. Thanks in advance