Betrayal trauma is defined as a trauma perpetrated by someone with whom the victim is close to and reliant upon for support and survival. The concept was originally introduced by Jennifer Freyd in 1994. Betrayal trauma theory (BTT) addresses situations when people or institutions on which a person relies for protection, resources, and survival violate the trust or well-being of that person. BTT emphasizes the importance of betrayal as a core antecedent of dissociation, implicitly aimed at preserving the relationship with the caregiver. BTT suggests that an individual (e.g. a child or spouse), being dependent on another (e.g. their caregiver or partner) for support, will have a higher need to dissociate traumatic experiences from conscious awareness in order to preserve the relationship.

Betrayal trauma theory emerged to integrate evolutionary processes, mental modules, social cognitions, and developmental needs with the extent to which the fundamental ethic of human relationships are violated. A foundational component of the dissociative aspect of BTT postulates that all humans possess an inherent mental mechanism to detect violations of social contracts (i.e., "cheater detectors"). BTT posits that in the context of abusive relationships in which escape is not a viable option, the cheater-detecting mechanism may be suppressed for the higher goal of survival. Thus, betrayal trauma offers a theory of psychogenic amnesia designed to evaluate both the role of attachment in human survival and the significance of blocking the painful experience.

Child sexual abuse (CSA) can involve molestation by one or more caregivers or close relatives. While physical and emotional abuse during childhood is present in the context of BTT, research has found that CSA leads to more significant disruption in capacities and is more characteristic of a substantial violation of human ethics. Notably, the degree to which one is violated by a caregiver or close relationship can influence the nature of and response to trauma. BTT suggests that CSA is closely linked with psychogenic amnesia or other dissociative processes occurring as a means to maintain an attachment with the caregiver and promote survival. For the victim to acknowledge the violation of CSA could increase their risk of impaired attachment provided by the caregiver and increase the potential of danger to the child. Such trauma has direct links to eliciting the process of "betrayal blindness". Similarly, evidence suggests that such trauma is more likely to be forgotten as compared to non-sexual childhood abuse. In order to help mitigate such trauma being forgotten or children being re-victimized, early interventions have been suggested. These early intervention efforts are thought to help with the long-term consequences of betrayal trauma.

Institutional betrayal refers to wrongdoings perpetrated when an institution fails to prevent or appropriately respond to wrongdoings by other individuals. In instances when individuals experiencing traumatic events place a great deal of trust in the legal, medical, and mental health systems to address their wrongs they risk disbelief, blame, and refusal of help. Priorities of the institution, such as protecting their reputation, may increase the likelihood that institutions fail to respond appropriately. Institutions may strenuously attempt to prevent knowledge of said assaults from surfacing, which can take the form of attempting to silence the individual. Lack of validation and interpersonal trauma from institutional betrayal can be examined through a BTT lens and have been described as a "second assault", which can exacerbate the effects of the initial trauma incurred.

Betrayal trauma via institutional betrayal can be particularly pervasive in environments that normalize abusive contexts, adopt procedures and policies that are unclear and potentially stigmatising, support cover-ups and misinformation, and punish victims and whistle blowers. Sexual assaults which take place on college campuses in which the system is unhelpful and unresponsive constitute BT. Similarly, sexual assault committed by close others in the context that the betrayal is implicit, and challenging to detect, has received increased attention in the media through campaigns oriented to highlight the prevalence of abuse in professional and academic institutions.

In the 2010s literature has expanded in this area to evaluate minority populations such as gender and sexual minorities (GSM), who may be at increased risk of experiencing institutional betrayal in academic institutions.

In an effort to directly measure institutional betrayal, results from comparisons of female veterans who experienced civilian sexual assault and those who experienced sexual assault in the United States military indicated that institutional betrayal was higher in military contexts when members were highly dependent upon the military for safety, protection, and employment. Although research investigating military sexual trauma (MST) is still in its infancy, literature has identified the perpetrator-victim relationship as a primary impediment to reporting the assault which could impact job status and contribute to disruptions in unit cohesion, ostracization, inability to leave or transfer duty stations.

Evidence evaluating the impact of assault or harassment during military service, and medical care is fraught with victim blaming and implicit policies of disrespectful treatment. Additionally emerging research has found that institutions (e.g., occupational settings, religious organizations, and schools) have the potential to worsen posttraumatic outcomes or be a source of social harm and injustice.