A measure of service individualization, derived from the goals in clients' treatment plans, was developed and used to evaluate this treatment process variable for 141 severely mentally ill persons served by three psychosocial rehabilitation programs. Relatively few of the 364 goals reviewed were highly individualized. Level of service individualization was inversely related to clients' functional skills, residential independence, level of education, and a primary diagnosis of an affective disorder, but positively related to a diagnosis of schizophrenia or another psychotic disorder. The goal individualization measure differentiated both between programs and among staff members, even after controlling for differences on client variables.