Objective Team formulation is advocated to improve quality of care in mental health care and evidence from a recent U.K.‐based trial supports its use in inpatient settings. This study aimed to identify the effects of formulation on practice from the perspectives of staff and patient participating in the trial, including barriers and enhancers to implementing the intervention. Method We carried out semistructured interviews with 57 staff and 20 patients. Data were analyzed using thematic analysis. Results Main outcomes were: improved staff understanding of patients, better team collaboration and increased staff awareness of their own feelings. Key contextual factors were as follows: overcoming both staff and patient anxiety, unwelcome expert versus collaborative stance, competing demands, and management support. Conclusion Team formulation should be implemented to improve quality of care in inpatient settings and larger definitive trials should be carried out to assess the effect of this intervention on patient outcomes.