Diarrhea remains the leading cause of mortality in both beef and dairy calves. Calves with diarrhea frequently develop dehydration, strong ion acidosis, electrolyte abnormalities, and are in a state of negative energy balance. The primary goals of treating calf diarrhea are to 1) correct free water and electrolyte abnormalities; 2) correct acid-base deficits (acidemia); 3) provide nutritional support; and 4) eliminate and/or prevent Escherichia coli bacteremia. There are many different ideas and approaches for how to "best" treat calf diarrhea. Some of these are supported by evidencebased medicine and others are not. The primary purpose of this article is to review some of the more common "ideas" associated with treating calf diarrhea that simply cannot be supported by data. We will try to highlight why these concepts are wrong and how to best approach treating the calf with scours.