In spite of increasing advocacy for patients’ participation in psychiatric decision-making, there has been little research on how patients actually participate in decision-making in psychiatric consultations. This study explores how patients take the initiative in decision-making over treatment in outpatient psychiatric consultations in Japan. Using the methodology of conversation analysis, we analyze 85 video-recorded ongoing consultations and find that patients select between two practices for taking the initiative in decision-making: making explicit requests for a treatment and displaying interest in a treatment without explicitly requesting it. A close inspection of transcribed interaction reveals that patients make explicit requests under the circumstances where they believe the candidate treatment is appropriate for their condition, whereas they merely display interest in a treatment when they are not certain about its appropriateness. By fitting practices to take the initiative in decision-making with the way they describe their current condition, patients are optimally managing their desire for particular treatments and the validity of their initiative actions. In conclusion, we argue that the orderly use of the two practices is one important resource for patients’ participation in treatment decision-making.