This investigation examined the reliability and validity of a rating scale for codependency in substance abuse treatment. The investigators developed an example-anchored rating scale to operationalize codependency as substance abuse counselors construe it in practice, and recruited 27 counselors for a counterbalanced multiple-treatment experiment. Counselors were randomly assigned to one of four continuing education workshops for rating-scale training, and asked to evaluate codependency in five videotaped cases. Semistructured case interviews were videotaped with a male and a female from five adult populations to vary the gender and codependency of cases: (1) outpatients in treatment for addiction, (2) outpatient spouses, (3) members of Codependents Anonymous, (4) United States Bureau of Land Management smoke jumpers, and (5) college students majoring in business or economics. To control for gender effects, one workshop presented male cases, one workshop presented female cases, and two workshops presented cases of both genders. To control for order effects, the assignment of videotapes to workshops was randomized to counterbalance the order in which counselors viewed them. The findings suggest that the rating scale yields reliable and valid evaluations of codependency without appreciable gender bias.