The assimilation model describes therapeutic change as an integration of experiences that had previously been problematic, distressing, avoided, or warded off. This study assessed whether assimilation was associated with treatment outcome in a sample of psychotherapeutic treatments for depression. Further, it assessed the direction of the association—whether increasing assimilation predicted decreases in symptom intensity or decreasing symptom intensity predicted increases in assimilation. Method Participants were 22 clients with mild to moderate depression drawn from a clinical trial comparing cognitive behavioral therapy with emotion‐focused therapy. The direction of prediction between assimilation progress and changes in self‐reported symptom intensity was assessed. Results The assimilation progress was shown to be a better predictor of decreases in symptom intensity than the reverse. Conclusion The results supported the assimilation model's suggestion that assimilation progress promotes decreases in symptom intensity in the treatment of clients with major depressive disorder.