Intended for professionals working with people with mental retardation and their families, this manual begins with a summary of the principles and philosophy concerning family participation and agency responsibilities of the South Carolina Department of Mental Retardation (DMR). The importance of family involvement in determining the least restrictive setting is stressed. Ten to 20 principles and guidelines are presented for the following activities: providing family-centered services, working with parents who are just learning of their child's disability, working with families routinely, resolving conflicts, developing effective partnerships, and working with families who aren't eligible for DMR services. A summary of key principles (e.g., remember parents are the experts on their child, be knowledgeable about resources available to the child and family, connect parents to other parents, and return telephone calls promptly) completes the guide. An appendix contrasts traditional ideas with state-of-the-art ideas concerning perceptions of disability and family roles, and contrasts myths with realities concerning parent participation in the decision making process. (DB)