Motivational interviewing (MI) is a patient-centered counseling technique used for behavior change. MI has been evaluated in hundreds of clinical trials across contexts, focusing on mental health and addictions. Despite promise as a technique in primary care, questions still remain around how MI might work, how best to measure clinician competence, and the extent to which this technique is transferable to different cultures. This dissertation seeks to understand how MI can be used in clinical settings. The first is a systematic review of MI for chronic disease. The second study presents a tool to measure clinician competence in Motivational interviewing and validates this against the current gold standard. Finally, the third study is a qualitative analysis of Singaporean clinicians and their views on incorporating MI into clinical practice.The meta-analysis shows that MI seems to be a useful tool in the prevention and management of chronic diseases. With a predominantly female sample, this technique indicates statistically significant effect sizes ranging between d=0.11 for physical activity, and d=1.01 for blood pressure. Subgroup analyses indicated stronger effects for US vs. international studies, in particular within US communities where there are high proportions of minority groups. In the second study, the validation of the OnePass tool for measuring MI competence, interrater reliability was good to excellent (between 0.44