Research findings are reviewed concerning infants' abilities to discriminate parents from other social stimuli during the first 6 months of life. The term "discrimination" is used to signify the ability of infants to respond differentially to two or more social stimuli. Studies reviewed are categorized in terms of the visual, auditory, multisensory, and intermodal sensory modalities investigated. Within each category, evidence of discrimination was evaluated for two groups: infants less than 12 weeks old and those from 12 to 26 weeks of age. This demarcation was made because the literature to date suggests, especially in the visual domain, that the most controversial evidence involves infants younger than 12 weeks. Supplementing the review of literature are appended tables summarizing 21 visual discrimination studies, 14 auditory discrimination studies, 25 multisensory studies, and 10 studies of intermodal person knowledge. Implications for theoretical and clinical issues in infant social development are briefly explored. (RH)