Background: Family studies of dystonia may be limited in part by small family size and incomplete ascertainment of dystonia in geographically dispersed famil ies. Further, prevalence estimates of dystonia are believed to be underestimates , as most studies are clinic- based and many individuals do not present to a ph ysician or are misdiagnosed. As a low- cost highly sensitive screening tool is needed to improve case detection for genetic and epidemiologic studies, the auth ors developed the Beth Israel Dystonia Screen (BIDS), a computer- assisted tele phone interview. Objective: To evaluate the validity and utility of a computer- assisted telephone interview in screening for cervical dystonia. Methods: The B IDS was administered and videotaped neurologic examinations performed on 193 ind ividuals from 16 families with cervical and cranial dystonia. With use of a fina l rating of definite dystonia, as determined by video review of a systematic neu rologic evaluation, as the gold standard, the predictive value of a subset of qu estions from the BIDS was assessed. Results: A positive response to at least two of five screening questions had a sensitivity for cervical dystonia of 100% a nd a specificity of 92% . With use of a positive response to three or more ques tions, definite dystonia was determined with 81% sensitivity and 97% specifi city. Conclusions: The Beth Israel Dystonia Screen (BIDS) identifies cervical dy stonia with excellent sensitivity and specificity in a family- based sample. Th e authors recommend the BIDS for family studies, but cross- validation in a pop ulation sample is advisable before applying this method to epidemiologic studies . Background: Family studies of dystonia may be limited in part by small family size and incomplete ascertainment of dystonia in geographically dispersed famil ies. Further, prevalence estimates of dystonia are believed to be underestimates, as most studies are clinic-based and many individuals do not present to a ph ysician or are misdiagnosed. As a low- cost highly sensitive screening tool is needed to improve case detection for genetic and epidemiologic studies, the auth ors developed the Beth Israel Dystonia Screen (BIDS), a computer-assisted tele phone interview Objective: To evaluate the validity and utility of a computer- assisted telephone interview in screening for cervical dystonia. Methods: The B IDS was administered and videotaped neurologic examinations performed on 193 ind ividuals from 16 families with cervical and cranial dystonia. With use of a fina l rating of definite dystonia, as determined by video review of a systematic neu rologic evaluation, as the gold standa rd, the predictive value of a subset of qu estions from the BIDS was assessed. Results: A positive response to at least two of five screening questions had a sensitivity for cervical dystonia of 100% a nd a specificity of 92%. Conclusions: The Beth Israel Dystonia Screen (BIDS) identifies cervical dy stonia with excellent sensitivity and specificity in a family-based sample. a positive response to three or more ques tions, definite dystonia was determined with 81% sensitivity and 97% specifi city. Th e authors recommend the BIDS for family studies, but cross- validation in a pop ulation sample is advisable before applying this method to epidemiologic studies.