ObjectiveDespite the clinical significance of emotional diversity, also known as emodiversity, there has been limited investigation into the therapeutic interventions that influence this construct. In the current study we examined the association between immediate therapist self‐disclosure (TSD) and emodiversity among two diagnostic groups who tend to experience emotional difficulties: people with schizophrenia and people with emotional disorders (i.e., depression and/or anxiety).MethodThe sample comprised 74 clients (37 diagnosed with schizophrenia and 37 with emotional disorders) treated by 45 therapists in a university clinic setting. Following each session, clients self‐reported their emotions, and therapists completed a measure of frequency and centrality of their immediate TSD during the session.ResultsLongitudinal multilevel models indicated that immediate TSD was positively associated with clients' global emodiversity, both at the within‐ and the between‐client levels, as well as with clients' negative emodiversity at the between‐client level. Moreover, clients with emotional disorders and clients with schizophrenia did not differ in the association between immediate TSD and emodiversity. In addition, across groups, clients treated by therapists who used more immediate TSD on average showed greater increases in global emodiversity during treatment.Conclusionsimmediate TSD is associated with clients' ability to experience rich and diverse emotional experiences across different disorders. The theoretical and clinical implications of these findings are discussed.