Expressive writing (EW) can be a useful supplement to psychotherapy, regardless of therapeutic orientation. In an open trial of exposure-based cognitive therapy for depression, 43 participants used EW before each session, producing 928 EW samples. Using examples from these, we discuss how EW can be used to both promote and track therapeutic change. Specifically, we review the impact of EW on therapeutic growth, via self-monitoring, increased awareness, and exposure/emotional processing. We then discuss how EW can be used to track important predictors of change such as symptoms, therapeutic alliance, social support, avoidance, and hopelessness. We conclude by discussing potential limitations to the use of EW in therapy and by recommending specific strategies for incorporating EW into clinical practice.