Behavioral inhibition (BI) discourages children from interacting, predisposing them to isolation, social anxiety, and depression. We have created the Behavioral Inhibition Scale for Children Aged 3 to 6 (BIS 3-6) to detect this trait early. Parents and teachers of 365 preschoolers completed different versions of the BIS 3-6 and provided measures of psychopathology. Both versions are structured into 1 factor that explains over 40% of total variability and displays excellent internal consistency ( =.95). The moderate correlations with measures of internalizing symptoms (r =.50) and nonexistent correlations with externalizing measures suggest adequate convergent and discriminant validity. A new scoring system is proposed. Copyright © Taylor & Francis Group, LLC.