Objective: Using propositions from Kiesler (1988)’s model of therapeutic metacommunication, this study investigated the relationship between therapist metacommunication and subsequent client collaboration and how this relationship was moderated by timing, therapist control, and affiliation. Building on Curran and Bauer (2011)’s data disaggregation approach, we examined the interaction of timing, between-session therapist control and affiliation, and within-session (between speaking-turn) therapist metacommunication. Method: The first 4 sessions from counseling dyads for 2 advanced students in an APA-accredited counseling psychology doctoral program and 1 licensed psychologist were recorded, transcribed, and coded for analysis. Client statements were coded for collaboration and therapist statements were coded for metacommunication, approach-avoidance (level of affiliation), and dominance-submission (level of control). Results: (a) There was a significant 3-way interaction of metacommunication, time, and between-session dominance-submission, such that metacommunication significantly predicted subsequent client collaboration in later speaking turns within a session, and when the therapist generally showed low dominance in that session. (b) There was a significant 3-way interaction of metacommunication, time, and between-session approach-avoidance. Specifically, early in sessions therapist approach buffered the negative effect of metacommunication on collaboration, and later in sessions therapist neutrality (less approaching) facilitated a positive effect of metacommunication on client collaboration. (c) There was a significant 2-way interaction of between-speaking-turn metacommunication and within-session time in predicting subsequent client collaboration, such that early in sessions metacommunication did not predict collaboration, whereas later in sessions more metacommunication was associated with higher collaboration. These results were discussed in relation to the therapeutic metacommunication model proposed by Kiesler (1988).