Place chicken, bbq sauce, and ranch dressing in a large ziplock bag. Seal bag shut and shake until the chicken is fully coated with the sauce. At this point, you can cook the chicken right away or marinate for 1 to 24 hours in the fridge.
Pre-heat oven to 375F. Line a baking dish with foil. Place chicken on prepared sheet pan and bake or grill for 30 minutes or until tender.