Although motivational interviewing (MI, Miller & Rollnick, 2002) is an integral part of efficacious college prevention approaches such as the Brief Alcohol Screening and Intervention for College Students (BASICS) program (Dimeff et al., 1999), little is known how the MI therapeutic style contributes to behavior change. Psychotherapy process methods specific to investigating the mechanisms of change related to MI were employed to examine how MI influences in-session and outcome behavior in a sub- sample of 97 sessions from two randomized controlled trials testing the efficacy of BASICS. Specifically, based on existing coding methods and informed by empirical findings, a coding system was developed to employ sequential analyses to examine the influence of peer provider global attributes and in-session behaviors consistent and inconsistent with the method of MI on in-session preparatory student change talk. The influence of student preparatory change talk on commitment language, and commitment language on behavior change, was subsequently evaluated. Results generally supported the hypothesized paths of the theoretical model of MI proposed by Miller & Rose (2009). With few exceptions, behaviors consistent with the method of MI were positively related to preparatory change talk, and behaviors inconsistent with the method of MI were positively related to increases in preparatory counter change talk. Preparatory change talk was positively associated with commitment language and commitment language in certain portions of the session was negatively associated with alcohol use and alcohol-related problems.