This commentary addresses four questions about using motivational interviewing (MI) with patients who have co-occurring schizophrenia and substance use disorders: (1) Has MI passed the threshold of an “evidence-based” approach when applied to dual diagnosis treatment? (2) How does MI work when used with patients who have psychotic disorders? (3) Which proposed MI modifications for these patients are efficacious or erroneous? (4) What are the implications for training clinicians in MI for use with this patient population? Upon contemplating the answers, the recommendation to use MI as a best dual diagnosis treatment practice may be premature.