Preheat oven to 350 F.
In a large bowl, mix together the chicken, mayonnaise, celery, water chestnuts, and sour cream. Scrape into an 11 x 7 x 2 in or other 2-quart baking dish. Sprinkle top with bread crumbs.
Bake in the oven for 20-25 minutes, or until the casserole is bubbly and the crumbs are lightly golden. Let the casserole stand for 10 minutes before serving.