Motivational Interviewing (MI) has demonstrated significant effects in diverse areas of practice, with over 2,000 controlled clinical trials published. Some criticisms of MI have emerged along the way.

We examine theoretical and methodological critiques of MI.

We discuss three significant theoretical and methodological criticisms of MI: (1) that MI lacks conceptual stability; (2) that MI lacks a theoretical foundation; and (3) that MI is just common factors in psychotherapy.

It is true that definitions and descriptions of MI have evolved over the years. Mastery of MI clearly varies across providers, and when the quality of an intervention is unmeasured, it is unclear what has been trained or delivered. Reliable and valid tools to assess MI fidelity are available but often unused in outcome studies. It remains unclear what levels of proficiency are necessary to improve client outcomes. Some attempts to minimize variability in the delivery of MI appear to have reduced its effectiveness. In respect of the second critique is that MI lacks a theoretical foundation. It is unclear whether and how this is a disadvantage in research and practice. Various theories have been proposed and specific causal chain predictions have been tested. A third critique is that MI is merely common factors found among psychotherapists. The contribution of such relational skills is testable. There are specific aspects of MI related to client language that influence client outcomes above and beyond its relational components.

The critiques reflect important factors to consider when delivering, training, and evaluating MI research.