Preheat the oven to 350 degrees F (175 degrees C).
In a medium bowl, mix together the green beans, sour cream, condensed soup, salt and pepper. Spoon into a 2 quart casserole dish. Stir melted butter into the crushed crackers, then sprinkle over the top of the casserole.
Bake for 30 minutes in the preheated oven, until lightly browned and bubbly.