A portion of the Tavistock Self-assessment Inventory has been proposed as a measure of social anxiety, which is postulated as a personal disposition to avoid public, visible, complex, socially evaluated behavior. 80 high school students' participation in school activities, rated on a 5-point scale from passive audience participation up to the most singular, focal leadership, was the criterion of validity, under the assumption that Ss scoring high in social anxiety would avoid the more focal, visible leadership positions in activities. With controls for two other variables known to affect participation, there was no evidence above the chance level favoring the behavioral validity of the Tavistock instrument with these Ss, suggesting that similar studies on adult Ss, the original standardization population, are in order.