Behavioral activation and experiential avoidance are considered closely related transdiagnostic constructs. Decreases in behavioral activation and increases in avoidance are both thought to play a role in the maintenance of emotional disorder symptoms. Using a series of random intercept cross-lagged panel models, this study examined the temporal relations between change in behavioral activation, experiential avoidance, and anxiety symptoms during outpatient administration of the Unified Protocol. Between-person results demonstrated that greater avoidance was associated with lower activation, and more severe anxiety symptoms were associated with both greater avoidance and lower activation. Within-person results suggested that improvements in avoidance tended to predict increased activation and decreased anxiety symptoms. Changes in activation did not substantially predict changes in avoidance or anxiety. Overall, these results provide preliminary information on the timing of important therapeutic processes and may shed light on how clinicians should prioritize targets.