Objective Counselor and client language have been identified as mechanisms of change in motivational interviewing (MI) counseling sessions. This study evaluated whether language patterns exhibited during MI sessions with substance users in the community would also be found during MI sessions with substance users in the criminal justice system. Method Forty audio recordings of MI sessions with substance‐using probationers were coded and analyzed sequentially using the Motivational Interviewing Skills Code (MISC) 2.5. Analyses examined the relationship between counselor and client language, and the relationship between client language and client substance use after 2 months. Results Counselor MI inconsistent language was associated with decreased change talk (lnOR = − 0.76, p < .05) though not with increased sustain talk. Both sustain talk (b = − 4.591, t = − 18.634 p < .001) and MI inconsistent language MIIN (b = − 4.419, t = − 19.886, p < .001) were positively associated with substance use at 2 months. Sustain talk early in the session (i.e., during deciles 1 and 2) was significantly greater among clients who reported using substances at 2 months, compared to clients who did not use substances. Conclusion These findings are broadly consistent with previous literature documenting the association between counselor language, client language, and client outcome.