Little attention has been given to measuring symptoms of separation anxiety (SA) in adulthood. The development of an Adult Separation Anxiety Questionnaire (ASA-27) is described and compared to a previously derived Adult Separation Anxiety Semistructured Interview (ASA-SI). Principal components analysis revealed a coherent construct of SA with high internal consistency (Cronbach's alpha =.95) and sound test-retest reliability (r =.86; P <.001). A receiver operation characteristic (ROC) analysis against the semistructured interview yielded a high area under the curve index (AUC = 0.9) suggesting that the questionnaire is an adequate alternative measure of SA. Results of this study support previous research suggesting that a construct of SA may be readily measured in adults.