Expectation states theory is a social psychological theory first proposed by Joseph Berger and his colleagues that explains how expected competence forms the basis for status hierarchies in small groups. The theory's best known branch, status characteristics theory, deals with the role that certain pieces of social information (e.g., race, gender, and specific abilities) play in organizing these hierarchies. More recently, sociologist Cecilia Ridgeway has utilized the theory to explain how beliefs about status become attached to different social groups and the implications this has for social inequality.

The theory attempts to explain: "When a task-oriented group is differentiated with respect to some external status characteristic, this status difference determines the observable power and prestige within the group whether or not the external status characteristic is related to the group task". In other words, the theory attempts to explain how hierarchies are created in small group interactions (with a shared goal) based on status cues. Specifically, this theory explains unequal distribution of participation, influence, and prestige between members of the group. This theory has implications for macro- and population-level hierarchy and inequality between groups.

In general, expectation states theory is meant to explain the way that interpersonal status hierarchies work. "Interpersonal status hierarchies" refers to the emergence of differential levels of social esteem and influence that occurs when groups of people interact. Research has found that several factors may influence the ways that status hierarchies emerge; however, the driving force seems to be implicit assumptions that group members hold about each other members' level of ability for completing the task at hand. Expectation states theory originated in the sociology literature and started with observations about differences in participation, influence, and prestige across members small groups, and these differences varied as a function of status characteristics.

The primary goal of expectation state theory as applied to gender is to explain how observed differences between social groups become the basis for inequality in everyday social encounters. While expectation states theory describes the development of status beliefs broadly, and can be applied to the study of any social groups, it is most commonly used to examine and explain inequality as it relates to gender.

In general, expectation states theory is meant to explain the way that interpersonal status hierarchies work (Berger et al., 1972). "Interpersonal status hierarchies" refers to the emergence of differential levels of social esteem and influence that occurs when groups of people interact. Research has found that several factors may influence the ways that status hierarchies emerge; however, the driving force seems to be implicit assumptions that group members hold about each other members' level of ability for completing the task at hand. Expectation states theory originated in the sociology literature and started with observations about differences in participation, influence, and prestige across members small groups, and these differences varied as a function of status characteristics.

Ridgeway (2011) also draws on status construction theory which states that as various groups (e.g. men and women) interact with each other over time, status hierarchies will often cause one group to be seen as more competent than the other. If this effect is repeated over time, the group with the higher status hierarchy will become more influential and the group with the lower status hierarchy will be more likely to give in to what the higher status group wants.

There are two types of status characteristics in status characteristics theory. (1) Diffuse status characteristics operates in a culture if (a) one state (i.e., male) is valued more than the other, and (b) that state is expected to be more competent at specific tasks, and (c) they are expected to generally be more competent at a wide variety of tasks. (2) Specific status characteristics do not have the third requirement (i.e., men are generally better than women at wide range of tasks; Berger et al., 1977).

Aspects of expectation state theory also draw on reward expectations theory which focuses on how status characteristics, abilities, and task accomplishment are related to expectations for rewards (Berger, Fiske, Norman, & Wagner, 1985). Reward expectations theory suggests that individuals who receive greater rewards are expected to be more competent than group members who do not receive high level of rewards.