Collective motivational interviewing (CMI) breaks new ground by extending the theory of motivational interviewing (MI) beyond the individual to include the social network. We explain the core concepts of the six-process model of CMI, which involves multiple parties in the motivational process in embodying a spirit of "neutrality." The semi-structured manual-guided CMI was trialed in persons with substance use with the support of concerned significant others (CSOs), which demonstrated positive outcomes on motivation, social support, frequency of drug use, and adherence to long-term drug treatments. Our developed CMI approach makes a clear contribution to the theory of MI and can potentially benefit people with substance use problems with complex needs. Presently, we are refining CMI and have been applying this approach to additional clients and CSOs. We call for more studies to monitor its fidelity and wider application in populations of individuals affected by substance use disorders. [ABSTRACT FROM AUTHOR]