In industrial and organizational psychology, organizational citizenship behavior (OCB) is a person's voluntary commitment within an organization or company that is not part of his or her contractual tasks. Organizational citizenship behavior has been studied since the late 1970s. Over the past three decades, interest in these behaviors has increased substantially.

Organizational behavior has been linked to overall organizational effectiveness, thus these types of employee behaviors have important consequences in the workplace.

Organ expanded upon Katz's (1964) original work.

Organ (1988) defines OCB as "individual behavior that is discretionary, not directly or explicitly recognized by the formal reward system, and that in the aggregate promotes the effective functioning of the organization". Organ's definition of OCB includes three critical aspects that are central to this construct:

At the same time, Organ's (1988) definition of OCB has generated a great deal of criticism. The very nature of the construct makes it difficult to operationally define. Critics started questioning whether or not OCBs, as defined by Organ, were discretionary in nature. Organ (1997), in response to criticisms, notes that since his original definition, jobs have moved away from a clearly defined set of tasks and responsibilities and have evolved into much more ambiguous roles. Without a defined role, it quickly becomes difficult to define what is discretionary.

OCB has often been compared to contextual performance. Similarly to OCB, this concept emerged in response to the realization that only looking at job specific work behaviors ignored a significant portion of the job domain. Originally, experts in this field focused only on activities that directly supported the output of the organization. As the job market became more aggressive, it became necessary for employees to go above and beyond that which is formally required by the job description in order to remain competitive. Contextual performance is defined as non-task related work behaviors and activities that contribute to the social and psychological aspects of the organization.

Contextual performance consists of four elements: persistence of enthusiasm, assistance to others, rule and proscribed procedure following, and openly defending the organizations objectives. OCB and contextual performance share their defining attributes as they both consist of behaviors other than those needed to perform the routine functions of the job. Both also require that these behaviors contribute to the overall success of the organization. Additionally, they also agree on the theme that these behaviors are discretionary and each employee chooses the amount and degree to which they will perform them. However, while contextual performance and OCB share a good part of their content domain, there are some important differences between the two constructs. One of the main requirements of OCBs is that they are not formally rewarded, which is not the case for contextual performance. Organ (1997) contends that OCBs may at some point encourage some sort of reward, but that these rewards would be indirect and uncertain. Also, contextual performance does not require that the behavior be extra-role, only that it be non-task. The differences between contextual performance and OCB are slight and easy to miss, however, they do exist.

OCB has also been compared to prosocial organizational behavior (POB). POB is defined as behavior within an organization that is aimed at improving the welfare of an individual, a group or an organization. The important distinction here is that this type of behavior, unlike OCB, can be unrelated to the organization. Thus, someone exhibiting prosocial behavior could be helping a coworker with personal matter.