Motivational interviewing (MI) is a clinical method that has evolved from a convergence of science and practice. It emphasizes two key components: a relational component focused on empathy and the interpersonal spirit of MI, and a technical component involving the differential evocation and reinforcement of client change talk. A causal chain model links therapist training, therapist and client responses during treatment sessions, and post-treatment outcomes. MI has been shown to be effective in promoting behavior change across various problems, including substance use, smoking, and diet. Research indicates that therapist empathy and client change talk are critical factors in MI's effectiveness. Studies have shown that MI can significantly increase client engagement and outcomes when combined with assessment feedback, such as in the "drinker's check-up." MI has also been found to enhance treatment outcomes when used as a prelude to other active treatments. However, its effectiveness can vary across populations and settings, highlighting the need for understanding the conditions under which MI works best. Research has also shown that MI training can improve clinician performance and client outcomes, with a focus on both relational and technical aspects of the method. Overall, MI is a promising clinical tool that can be integrated with other evidence-based methods to address client ambivalence and motivation.Motivational interviewing (MI) is a clinical method that has evolved from a convergence of science and practice. It emphasizes two key components: a relational component focused on empathy and the interpersonal spirit of MI, and a technical component involving the differential evocation and reinforcement of client change talk. A causal chain model links therapist training, therapist and client responses during treatment sessions, and post-treatment outcomes. MI has been shown to be effective in promoting behavior change across various problems, including substance use, smoking, and diet. Research indicates that therapist empathy and client change talk are critical factors in MI's effectiveness. Studies have shown that MI can significantly increase client engagement and outcomes when combined with assessment feedback, such as in the "drinker's check-up." MI has also been found to enhance treatment outcomes when used as a prelude to other active treatments. However, its effectiveness can vary across populations and settings, highlighting the need for understanding the conditions under which MI works best. Research has also shown that MI training can improve clinician performance and client outcomes, with a focus on both relational and technical aspects of the method. Overall, MI is a promising clinical tool that can be integrated with other evidence-based methods to address client ambivalence and motivation.