The measurement of avoidance behavior in youth with anxiety and related disorders is essential. Historically, the behavioral avoidance task (BAT) has been used as a measure of avoidance that can be tailored to a youth’s particular fear. Although in use for over 90 years, there has yet to be a systematic review of its use, properties, etc. Here we examine the use of the BAT with youth as a measure of avoidance over the past 30 years. Studies have used the BAT as a measure of treatment outcome, to explore theories related to avoidance, and provide evidence for the psychometric properties of phobia questionnaires. Specifically, we compare the results of these studies, the purposes of the BAT, and the types of data collected. Results indicated that the BAT might be particularly sensitive to treatment effects. Furthermore, youth with specific phobias can be expected to complete an average of 30% of the BAT at pre-treatment and 60% at post-treatment. These affects have generally been maintained at 6-month follow-ups. Measures of subjective units of distress (SUDS) proved more consistent than steps completed, but more resistant to treatment effects; researchers can expect a SUDS rating of approximately 55% at pre-treatment and 40% at post-treatment. We review the properties and procedures that are used within these studies and provide a critical review. Overall, the BAT is in need of a standardized procedure to allow for psychometric studies to provide evidence of the task’s reliability and validity.