Relative deprivation is the lack of resources to sustain the diet, lifestyle, activities and amenities that an individual or group are accustomed to or that are widely encouraged or approved in the society to which they belong.  Measuring relative deprivation allows an objective comparison between the situation of the individual or group compared to the rest of society. Relative deprivation may also emphasise the individual experience of discontent when being deprived of something to which one believes oneself to be entitled, however emphasizing the perspective of the individual makes objective measurement problematic.   
It is a term used in social sciences to describe feelings or measures of economic, political, or social deprivation that are relative rather than absolute.  The term is inextricably linked to the similar terms poverty and social exclusion.  The concept of relative deprivation has important consequences for both behavior and attitudes, including feelings of stress, political attitudes, and participation in collective action. It is relevant to researchers studying multiple fields in social sciences.  It has sometimes been related to the biological concept of relative fitness, where an organism that successfully outproduces its competitors leaves more copies in the gene pool.[ citation needed]
Social scientists, particularly political scientists and sociologists, have cited 'relative deprivation' (especially temporal relative deprivation) as a potential cause of social movements and deviance, leading in extreme situations to political violence such as rioting, terrorism, civil wars and other instances of social deviance such as crime.   For example, some scholars of social movements explain their rise by citing grievances of people who feel deprived of what they perceive as values to which they are entitled.  Similarly, individuals engage in deviant behaviors when their means do not match their goals. 
American sociologist Robert K. Merton was among the first (if not the first) to use the concept of relative deprivation in order to understand social deviance, using French sociologist Emile Durkheim's concept of anomie as a starting point.[ citation needed]
- Person A does not have X
- Person A knows of other persons that have X
- Person A wants to have X
- Person A believes obtaining X is realistic
Runciman distinguishes between egoistic and fraternalistic relative deprivation. The former is caused by unfavorable social position when compared to other, better off members of a specific group (of which A is the member) and the latter, by unfavorable comparison to other, better off groups. Egoistic relative deprivation can be seen in the example of a worker who believes he should have been promoted faster and may lead that person to take actions intended to improve his position within the group; those actions are, however, unlikely to affect many people. Fraternalistic can be seen in the example of racial discrimination, and are much more likely to result in the creation and growth of large social movement, like the American Civil Rights Movement in the 1960s. Another example of fraternalistic relative deprivation is the envy teenagers feel towards the wealthy characters who are portrayed in movies and on television as being "middle class" or "normal" despite wearing expensive clothes, driving expensive cars, and living in mansions. Fraternalistic group deprivation has also been linked to voting behaviours, particularly in the case of voting for the far-right .
Deprivation Theory means that people who are deprived of things deemed valuable in society—whether money, justice, status or privilege—join social movements with the hope of redressing their grievances. This is a beginning point for looking at why people join social movements; however, it is even more important to look at relative deprivation theory, a belief that people join social movement based on their evaluations of what they think they should have compared with what others have. On the contrary, absolute deprivation is people's actual negative condition; relative deprivation is what people think they should have relative to what others have, or even compared with their own past or perceived future. Improved conditions fuel human desires for even better conditions, and thus can spark revolutions.
Feelings of deprivation are relative, as they come from a comparison to social norms that are not absolute and usually differ from time and place. This differentiates relative deprivation from objective deprivation (also known as absolute deprivation or absolute poverty) - a condition that applies to all underprivileged people. This leads to an important conclusion: while the objective deprivation (poverty) in the world may change over time, relative deprivation will not, as long as social inequality persists and some humans are better off than others.
Consider the following examples: in 1905 cars were a luxury, hence an individual unable to afford one would not feel or be viewed as deprived. In 2010, when cars are common in most societies, an individual unable to afford one is much more likely to feel deprived. In another example, mobile phones are common today, and many people may feel that they deserve to have one. Fifty years ago, when there were no mobile phones, such a sentiment would obviously not exist.
Relative deprivation may be temporal; that is, it can be experienced by people that experience expansion of rights or wealth, followed by stagnation or reversal of those gains. Such phenomena are also known as unfulfilled rising expectations. 
In an example from the political realm, the lack of the right to vote is more likely to be felt as a deprivation by people who had it once than by the people who never had the opportunity to vote.
Some sociologists, for instance Karl Polanyi, have argued that relative differences in economic wealth are more important than absolute deprivation, and that it is more significant in determining human quality of life.  This debate has important consequences for social policy, particularly on whether poverty can be eliminated simply by raising total wealth or whether egalitarian measures are also needed.
A specific form of relative deprivation is relative poverty. A measure of relative poverty defines poverty as being below some relative poverty line, such as households who earn less than 20% of the median income.
Critique of this theory has pointed out that this theory fails to explain why some people who feel discontent fail to take action and join social movements. Counter-arguments include that some people are prone to conflict-avoidance, are short-term-oriented, and that imminent life difficulties may arise since there is no guarantee that life-improvement will result from social action. 
Consider also this quotation from Karl Marx: "A house may be large or small; as long as the neighboring houses are likewise small, it satisfies all social requirement for a residence. But let there arise next to the little house a palace, and the little house shrinks to a hut. The little house now makes it clear that its inmate has no social position at all to maintain, or but a very insignificant one; and however high it may shoot up in the course of civilization, if the neighboring palace rises in equal or even in greater measure, the occupant of the relatively little house will always find himself more uncomfortable, more dissatisfied, more cramped within his four walls." 
- Peter Townsend, Poverty in the United Kingdom : A Survey of household resources and standards of living, Penguin Books, 1979, ISBN 0-520-039769, 
- Iain Walker, Heather J. Smith, Relative Deprivation: Specification, Development, and Integration, Cambridge University Press, 2001, ISBN 0-521-80132-X, Google Books
- Kurt Bayertz, Solidarity, Springer, 1999, ISBN 0-7923-5475-3, Google Print p.144
- Schaefer defines it as "the conscious experience of a negative discrepancy between legitimate expectations and present actualities.Richard T. Schaefer, Racial and Ethnic Groups, 11th Ed., not in this book Pearson Education, 2008, p.69
- "Relative Poverty, Absolute Poverty and Social Exclusion". Retrieved 2014-01-04. 
- Robert K. Merton, "Social Structure and Anomie". American Sociological Review 3: 672-82, 1938.
- Ted Robert Gurr, Why Men Rebel, Princeton University Press, 1970, ISBN 0-691-07528-X
- Jerry D. Rose, Outbreaks, the sociology of collective behavior, 1982, New York Free Press, ISBN 0-02-926790-0
- Dambrun, M., Taylor, D. M., McDonald, D. A., Crush, J., & Méot, A. (2006). The relative deprivation-gratification continuum and the attitudes of South Africans toward immigrants: a test of the V-curve hypothesis. Journal of Personality and Social Psychology, 91(6), 1032.
- Dambrun, M., & Taylor, D. M. (2013). The Counterintuitive Association Between Life Satisfaction and Racism. SAGE Open, 3(3), 2158244013505756.
- * Walter Garrison Runciman, Relative deprivation and social justice : a study of attitudes to social inequality in twentieth-century England, University of California Press, 1966
- Urbanska, Karolina; Guimond, Serge (2018-10-26). "Swaying to the Extreme: Group Relative Deprivation Predicts Voting for an Extreme Right Party in the French Presidential Election". International Review of Social Psychology. 31 (1). doi: 10.5334/irsp.201. ISSN 2397-8570.
- Diana Kendall, Sociology In Our Times, Thomson Wadsworth, 2005, ISBN 0-534-64629-8 Google Print, p.530
- David R. Griffin, Spirituality and Society: Postmodern Visions, SUNY Press, 1988, ISBN 0-88706-853-7 Google Print, p.29
- Karl Marx (1847). "Relation of Wage-Labour to Capital". Wage Labour and Capital. Translated by Frederick Engels.
- James M. Olson, C. Peter Herman, Mark P. Zanna (ed.), Relative Deprivation and Social Comparison, Lawrence Erlbaum Associates, 1986, ISBN 0-89859-704-8, Google Print
- Wallace, Anthony F.C. 1956. "Revitalization Movements," American Anthropologist 58: 264-281.