There is no doubt that a variety of factors contribute to a counseling group's effectiveness. These factors include those that pertain to the counselor and those related to the group. The literature on the counselor variables discusses what personality characteristics influence the group's effectiveness, how certain demographic variables influence the group, or how the counselor's style affects the group.The counselor's personality and style can be the best predictors of whether participants are helped or hurt in a group (Cooper, 1977). Kellerman (1979) lists a number of personality traits he considers desirable, including simplicity, honesty, straightforwardness, an ability to succeed, commitment to diversity, tolerance, authenticity, trust, ability to empathize, warmth, acceptance, understanding, spontaneity, capability of maintaining distance, experimentation, sense of humor, and capability of assuming a wide variety of group roles. A study by Snyder (1978) found that counselors with an external locus of control produced greater changes in group members than those with internal loci of control.