The common good or common weal is a term that can refer to several different concepts. In the popular meaning, the common good describes a specific "good" that is shared and beneficial for all (or most) members of a given community. This is also how the common good is broadly defined in philosophy, ethics, and political science.

However there is no strict definition of the common good for each situation. The good that is common between person A and person B may not be the same as between person A and person C. Thus the common good can often change, although there are some things such as the basic requirements for staying alive: food, water, and shelter - that are always good for all people.

The common good has sometimes been seen as a utilitarian ideal, thus representing "the greatest possible good for the greatest possible number of individuals". In the best case scenario, the "greatest possible number of individuals" would mean all sentient beings. This definition of the common good presents it as a quality which is convertible, or reducible, to the sum total of all the private interests of the individual members of a society and interchangeable with them. But this is a narrow, and many would argue impoverished, view of what the common good might encompass.