A quantitative ethogram was developed for the Zebra finch, using one-zero focal animal sampling on an ethologically comprehensive checklist of 52 behavioral items, and was assessed for both interobserver reliability and construct validity. Interobserver reliabilities were highly acceptable (an eta-squared of, 923 for aggregation periods of 5 minutes). Nine common factors (Singing & Parenting, Social Proximity, Social Contact, Social Submission, Social Aggression, Sex & Violence, Object Handling, Surface Foraging, and General Activity) produced highly acceptable convergent validities (high factor loadings for most behavioral items) and discriminant validities (low factor intercorrelations). Applying the quantitative methods of psychometrics thus permits the verification of ethological theory and the testing of diverse hypotheses with a high degree of sophistication.