Many clients drop out of therapy before reaching their goals, (Bohart & Wade, 2013) though research shows that being in therapy is more effective in producing change than not being in therapy, (Lambert, 1992). Little is known about what makes therapy effective (Davis & Piercy, 2007a, b; Pinsof & Wynne, 2000). The purpose of the present study was to understand what clients believe is productive about therapy, and how clients’ assessment of therapy productiveness impacts their decision to remain in therapy or to drop out of therapy. For the qualitative strand of this simultaneous convergent mixed methods study, grounded theory was used to inductively develop a common-factors informed model describing how productive change processes influence intended retention. The convenience sample consisted of 19 current clients in therapy with a marriage and family therapist. For the quantitative strand, participation involved completing a semi-structured interview and quantitative survey. Direct, binary logistic regression analyses were conducted to determine whether perceived productiveness, goal attainment and therapeutic alliance, predicted intended treatment retention or intended dropout. The convenience sample for quantitative analysis included the 19 qualitative participants, and continued sampling until adequate statistical power was reached with 72 participants. Mixed analysis strategy was data comparison for the purpose of triangulation. Qualitative results span three categories emerged from qualitative: client factors, therapy process factors and evaluation of progress. Client factors, including presenting problem factors, expectations and motivation were considered when participants made decisions about staying in therapy or dropping out of iii therapy. Therapy process factors, including therapists’ understanding of the presenting problem, therapeutic alliance, therapists interventions and the pacing and timing of those interventions were also considered when participants made decisions about staying in therapy or dropping out of therapy. When participants evaluated the progress made because of therapy, they evaluated changes in the presenting problem, symptom reduction, and noticed this progress took place outside of therapy. Quantitative results showed that goal attainment, therapeutic alliance and productiveness significantly predicted intended retention when each was tested as an individual predictor. When tested in a full model, containing goal attainment, therapeutic alliance and productiveness; only the task domain of therapeutic alliance emerged as significant. Results confirm the importance of therapeutic tasks to clients’ decision to stay in therapy or to drop out of therapy. Results contribute to the importance of common factors in keeping clients in therapy until they reach their goals. Further, results inform research, clinical practice and training in the MFT field.