Compulsivity and obsessiveness are vaguely defined terms which include a broad range of behaviors and cognitions that have been elusive to quantify. To introduce the 22-item Obsessive-Compulsive Scale (OCS) and to perform preliminary validation studies, 114 (46 male, 68 female) college students and 57 counseling clients completed the OCS on two separate occasions. To determine test validity, the Orderliness Scale of the Comrey Personality Scales and the Change Scale of the Adjective Check List (ACL) were also administered. Further validation was obtained from psychologists' assessment of the 57 clients and ratings of the participants by roommates. An analysis of the results showed that the OCS had a modest level of reliability and promising concurrent validity. Correlations with the ACL and the Comrey Order Scale also were within the modest range. No differences between means were found for sex or client versus student subgroups. Further validation studies and the development of norms is recommended. (The OCS and tables presenting the means, standard deviations, and correlations of the OCS with other measures are appended.) (BL)