Pediatric anxiety disorders are common, disabling, and chronic conditions. Efforts over the past two decades have focused on developing and testing effective treatments. Short-term efficacy of both Cognitive Behavioral Therapy (CBT) and selective serotonin reuptake inhibitors has been established. Data are emerging on the long-term (i.e., 2 years or longer) effectiveness of these treatments, but this literature has yet to be adequately synthesized. This study presents a systematic and critical qualitative review of published long-term follow-up (LTFU) studies of youth treated for an anxiety disorder. A comprehensive search of several databases identified 21 published reports (representing 15 LTFU cohorts of treated youth) meeting specified inclusion criteria. LTFU assessments occurred a mean of 5.85 years after initial treatment (range 2–19 years). Diagnostic rates at LTFU and predictors (e.g., demographic, baseline child clinical variables, treatment type) of outcomes at LTFU were also examined. A discussion of the limitations of this literature is provided to qualify interpretations of findings and to inform future studies. Findings can aid clinicians and families in making treatment decisions and setting reasonable expectations for the long-term prognosis after treatment for anxiety.