>Sometimes when creating a parent child relationship the child may need to know who it's parent is.
>
>I can do that easy enough by passing the parent reference in the constructor for the child.
>
>In C# do I need to worry about the circular reference I've just created?

Not 100% sure of your context. Bonnie mentioned the problem with assemblies but I think you're asking about simple objects like:

public class ClassA
    {
        ClassB B;
        public ClassA(ClassB b)
        { B = b; }
    }

    public class ClassB
    {
        ClassA A;
        public ClassB()
        {A = new ClassA(this);}
    }

If so then there's not a problem. See:http://msdn.microsoft.com/en-us/library/0t81zye4(VS.71).aspx

Best,
Viv