Treatment integrity ratings (adherence and competence) are frequently used as outcome measures in clinician training studies, drawn from recorded real client or role-played client sessions. However, it is unknown whether clinician adherence and competence are similar in real client and role-played sessions or whether real and role-play clients provide similar opportunities for skill demonstration. In this study, we examined the correspondence of treatment adherence and competence ratings obtained in real client and role-played sessions for 91 clinicians trained in motivational interviewing (MI), using data from a multisite trial examining 3 methods of clinician training (Martino et al., 2011). Results indicated overall poor integrity rating correspondence across the 2 session types, as indicated by weak correlations (rs = .05–.27). Clinicians were rated significantly more MI adherent overall and specifically used more advanced MI strategies in role-played than real client sessions at several assessment time points (ds = 0.36, 0.42). Real clients, in comparison to the role-play actor, demonstrated greater motivation at the beginning of the session (d = 1.09), discussion of unrelated topics (d = 0.70), and alliance with the clinician (d = 0.72). These findings suggest that MI integrity rating data obtained from real client and role-played sessions may not be interchangeable. More research is needed to improve the procedures and psychometric strength of treatment integrity assessment based on role-played sessions.