This paper reviews recent literature related to co-worker involvement in non-sheltered community-based employment programs for persons with mental retardation. Discussion of co-worker roles is categorized into six areas: training, associating, befriending, advocating, evaluating, and information giving. Also discussed are other variables potentially influencing co-worker involvement, including integration variables (physical integration, social integration, and vocational integration) and factors related to characteristics of individuals, the employment site, and employment in general (supported employment model, type of job, etc.). The existing research shows that co-workers are involved with employees with handicaps in at least the six areas described. Includes 41 references. (Author/DB)