Beneficence is a term in medical ethics; it means to act for the benefit of others, helping them to further their important and legitimate interests, often by preventing or removing possible harms.

It is the duty to act in the best interest of the patient, client, or resident.

It must be distinguished from "paternalism" (or "parentalism").
Strong paternalism is the intentional imposing on an unwilling or uninformed person some action that is considered to be in their best interest, even though the person may disagree. It ignores the principle of autonomy.
Weak paternalism is a similar action when persons are vulnerable and likely to make poor decisions; the aim is to help them to restore their autonomy.

Adapted from Gillon R. Medical ethics: four principles plus attention to scope. BMJ 1994;309:184. Internet. Accessed on August 21, 2011.