Small beer is a beer that contains very little alcohol, perhaps less than one percent. Sometimes unfiltered and porridge-like, it was a favored drink in Medieval Europe and colonial North America. It was sometimes had with breakfast, as attested in Benjamin Franklin's autobiography. Before public sanitation, water-transmitted diseases, such as cholera, were a significant cause of death. Because alcohol is toxic to most water-borne pathogens, and because the process of brewing any beer from malt involves boiling the water, which also kills them, drinking small beer instead of water was one way to escape infection.

Small beer is not made in any significant amount today, though a similar product called non-alcoholic beer (which actually has a little alcohol) is quite common.

Metaphorically, small beer means a trifle, a thing of little importance.