BACKGROUND: Anxiety disorders are prevalent and associated with substantial distress and impairment. Within the metacognitive model of emotional disorders, the cognitive attentional syndrome (CAS) and associated metacognitions maintain anxiety. The Attention Training Technique (ATT) targets the CAS and related metacognitions. However, less is known about how symptoms and metacognitive mechanisms evolve across treatment phases. OBJECTIVE: The study aimed to explore temporal dynamics in emotional symptoms and metacognitive mechanisms during group ATT by estimating mean levels, variability, and coupling across the pre-, during-, and post-treatment phases using ecological momentary assessment (EMA). METHOD: Nineteen young adults with social anxiety disorder, panic disorder with agoraphobia, or generalized anxiety disorder participated. EMA was completed four times daily over six weeks: two weeks before treatment, two weeks during treatment, and two weeks after treatment. Each assessment included ten items measuring emotional symptoms (e.g., nervousness) and metacognitive mechanisms (e.g., worry, uncontrollability). RESULTS: Three patterns of change emerged: (1) reduced mean levels without change in variability (nervousness, self-consciousness, and worry); (2) reduced mean levels and reduced variability (threat monitoring); and (3) reduced mean levels and reduced variability during treatment, followed by an increase in variability after treatment (uncontrollability, difficulty collecting thoughts, and meta-worry). CONCLUSIONS: The findings provide new insights into dynamic patterns of change in symptoms and metacognitive mechanisms before, during, and after ATT. Patterns of change in both intensity and stability may be relevant for understanding treatment response and vulnerability following treatment, suggesting the potential clinical relevance of monitoring these mechanisms.