Evaluation research on vocational counseling in substance dependency treatment should distinguish between the effects of counselors and counseling methods on clients' employment outcomes. Three experimental designs permit investigation of possible confounds between these types of effects: (a) nested designs (each counselor delivers one counseling method so counselors are nested under methods), (b) crossed designs (each counselor delivers all counseling methods so counselors are crossed with methods), and (c) no-treatment control group designs (experimental group's counselors all deliver the same method). Each design is optimal for one stage of evaluation research. No-treatment control group designs are best for exploratory evaluations of new types of vocational counseling. Nested designs are best for outcome evaluations of different types of interventions. Crossed designs are best for (causal) process evaluations of counseling methods of demonstrated efficacy. Despite the importance of methodological issues and problems, vocational rehabilitation in substance dependency treatment has a greater need for stronger interventions than better evaluation designs. (Contains 2 tables.)