Toleration and tolerance are terms used in social, cultural and religious contexts to describe attitudes which are "tolerant" (or moderately respectful) of practices or group memberships that may be disapproved of by those in the majority. In practice, "tolerance" indicates support for practices that prohibit ethnic and religious discrimination. Conversely, 'intolerance' may be used to refer to the discriminatory practices sought to be prohibited. Though developed to refer to the religious toleration of minority religious sects following the Protestant Reformation, these terms are increasingly used to refer to a wider range of tolerated practices and groups, or of political parties or ideas widely considered objectionable.

The concept of toleration is controversial. For one, "toleration" does not raise the level of an actual principle or ethic, such as other concepts (respect, reciprocity, love) do. Liberal critics may see in it an inappropriate implication that the "tolerated" custom or behavior is an aberration or that authorities have a right to punish difference; such critics may instead emphasise notions such as civility, pluralism, or respect. Other critics may regard a narrow definition of 'tolerance' as more useful, since it does not require a false expression of enthusiasm for groups or practices which are genuinely disapproved of.

As a practical matter, governments have always had to consider the question of which groups and practices to tolerate and which to persecute. The Edicts of Ashoka issued by Ashoka the Great in the Maurya Empire declared ethnic and religious tolerance. The later expanding Roman Empire faced the question of whether or to what extent practices or beliefs could be tolerated or vigorously persecuted. Likewise, during the Middle Ages, the rulers of Christian Europe or the Muslim Middle East sometimes extended toleration to minority religious groups, and sometimes did not. Jews in particular suffered under anti-Semitic persecutions in medieval Europe.Vartan Gregorian, "Islam: A Mosaic, Not a Monolith", Brookings Institution Press, 2003, pg 26-38 ISBN 081573283X A notable exception was Poland, which served as a haven for European Jewry because of its relative tolerance - by the mid-sixteenth century, 80 percent of the world's Jews lived in Poland.

An early champion of toleration in Europe was Pawel Wlodkowic, who at the Council of Constance advocated the pagan nations' rights. However, the development of a body of theory on the subject of toleration didn't begin until the sixteenth and seventeenth centuries, in response to the Protestant Reformation and the Wars of Religion and persecutions that followed the breaks with the Catholic Church instigated by Martin Luther and Huldrych Zwingli and others. In response to the theory of persecution that was used to justify wars of religion and the execution of persons convicted of heresy and witchcraft, writers such as Sebastian Castellio and Michel de Montaigne questioned the morality of religious persecution, and offered arguments for toleration. By contrast, Poland, which had been uniquely tolerant and ethnically as well as religiously diverse, officially confirmed its status as "a place of shelter for heretics" in the Confederation of Warsaw of 1573, the first toleration act in Europe.