Open Dialogue is an alternative approach for treating psychosis as well as other mental health disorders developed in the 1980s in Finland by Yrjö Alanen and his collaborators. Open Dialogue interventions are currently being trialed in several other countries including Australia, Belgium, Denmark, Germany, Italy, Norway, Poland, the United Kingdom, and the United States. In Israel there is a non-governmental organization called Open Dialogue Israel.

Open Dialogue (OD) developed from Need-Adapted Treatment as described by Alanen and colleagues in the early 1990s. This approach took shape within the mental health services of Finnish Western Lapland in the 1980s and 1990s. During its initial research and training in psychotherapy, seven key principles were identified:

The first five principles focus on the organizational aspects of delivering mental health services; the last two principles are about the conversational methods mental health professionals use in network meetings with clients. The participation of friends and family, responding to the client's utterances, trying to make meaning of what a client has to say, and "tolerating uncertainty".

A recently published global survey on the worldwide implementation of Open Dialogue in mental health services gathered data from 142 Open Dialogue teams in 24 countries, mainly in Europe. Key factors enhancing Open Dialogue implementation included well-trained staff, regular supervisions, research capabilities, diverse professional teams, self-referrals, outpatient services, younger clients, and the involvement of experts by experience. The study underscores the importance of more Open Dialogue training, supervision, and research.

In a paper illustrating the Open Dialogue method Seikkula, Alakar and Aaltonen postulate that "from the social constructionist point of view, psychosis can be seen as one way of dealing with terrifying experience in one's life that do not have language other than the one of hallucinations and delusions" and that "psychotic reactions should be seen [as] attempts to make sense of one's experiences that are so heavy that they have made it impossible to construct a rational spoken narrative" arguing that people may talk about such experiences in metaphor.

They offer a model that "psychotic reactions greatly resemble traumatic experiences" with experiences of victimization "not being stored in the part of the memory system that promotes sense-making". Postulating that "an Open Dialogue, without any preplanned themes or forms seems to be important in enabling the construction of a new language in which to express difficult events in one's life."

This understanding differs radically from common psychiatric models of psychosis that view it as being caused by a biological process in the brain, such as the dopamine hypothesis of schizophrenia.^{[citation needed]}

Although pilot treatments since the 1980s show improved reintegration and a reduction in the need for medication, a systematic review of academic publications on the topic in 2018 concluded that "further studies are needed in a real-world setting to explore how and why [Open Dialogue] works", remarking that "most studies were highly biased and of low quality".