Acceptance is a cognitive activity or state that is the opposite of resistance. Lack of acceptance of things that cannot be changed can contribute towards negative mental states such as depression or anxiety.

Increasing one's acceptance of oneself and one's life was part of the Buddha's teachings. Through the first noble truth, 'Life is suffering', he invites people to accept that suffering is a natural part of life.

Note that acceptance is not the same as approval, sympathy, liking etc. A dictionary definition of the word may list approval as a synonym, but another definition may list tolerance as one. Acceptance means agreeing that something will happen or has happened, and living with it regardless of whether one previously liked it or not. Approval indicates judging something to be the right thing to do/happen. Sympathy means affinity for something, which is beyond acceptance, although the verb to sympathise means to be understanding of something, which is closer to the meaning of acceptance. Liking means wanting something to happen.

Minority groups in society often describe their goal as "acceptance". In this case, it means for the majority to allow them full participation on equal terms in all aspects of society. Acceptance is often contrasted to tolerance, in which the minority is allowed to exist unmolested but not fully accepted.