Can I have an Action or Func with an out param?

Action and Func specifically do not take out or ref parameters. However, they are just delegates.

You can make a custom delegate type that does take an out parameter, and use it, though.

For example, the following works:

class Program
{
    static void OutFunc(out int a, out int b) { a = b = 0; }

    public delegate void OutAction<T1,T2>(out T1 a, out T2 b);

    static void Main(string[] args)
    {
        OutAction<int, int> action = OutFunc;
        int a = 3, b = 5;
        Console.WriteLine("{0}/{1}",a,b);
        action(out a, out b);
        Console.WriteLine("{0}/{1}", a, b);
        Console.ReadKey();
    }
}

This prints out:

3/5
0/0