access from one of this childs to a method in Master Form

Question

I am a user of c#, visual studio 2005.

I have a principal MDI  Master Form that launch mdi childrens. I need to access from one of this childs to a method in Master Form.
How can I do this?

 Must I use delegates?
 Static methods? (if static, my problem is that I can call Master's method from child but this method isn't able to accessing form controls.)