Presented for diagnosticians and referral agents is an overview of four major types of diagnostic procedures utilized in the assessment of mental retardation: differential, etiological, diagnostic-remedial, and behavioral-task analysis. The rationale, definition, method, assets, and limitations of each method are discussed and are summarized in chart form. The chart also includes information on the tools, referral procedures, time and cost, and training needed for each method. (LS)