Autosizing a grid column to take up remaining space in parent

Question

In WPF, I am having a heck of a time trying to get a grid to size properly.

I have the following layout for my grid:

Answer 1

Seems I found a solution after a bit more tinkering around.

The problem was:

This was causing the column to fit to the content. I changed it to:

This causes the column to fit to the empty space left in the parent container, regardless of content size.