Indoctrination is the process of inculcating a person with ideas, attitudes, cognitive strategies or professional methodologies (see doctrine).

Humans are a social animal species inescapably shaped by cultural context, and thus some degree of indoctrination is implicit in the parent–child relationship, and has an essential function in forming stable communities of shared values, and thus should not be regarded as harmful, and is probably good or prosocial.

The precise boundary between education and indoctrination often lies in the eye of the beholder. Some distinguish indoctrination from education on the basis that the indoctrinated person is expected not to question or critically examine the doctrine they have learned. As such the term may be used pejoratively or as a buzz word, often in the context of political opinions, theology, religious dogma or anti-religious convictions. The word itself came about in its first form in the 1620s as endoctrinate, meaning to teach or to instruct, and was modeled from French or Latin. The word only gained the meaning of imbuing with an idea or opinion in the 1830s.

The term is closely linked to socialization; however, in common discourse, indoctrination is often associated with negative connotations, while socialization functions as a generic descriptor conveying no specific value or connotation (some choosing to hear socialization as an inherently positive and necessary contribution to social order, others choosing to hear socialization as primarily an instrument of social oppression). Matters of doctrine (and indoctrination) have been contentious and divisive in human society dating back to antiquity. The expression attributed to Titus Lucretius Carus in the first century BCE quod ali cibus est aliis fuat acre venenum (what is food to one, is to others bitter poison) remains pertinent.