A method for direct observation study of early peer-social and object directed behavior in humans was designed to articulate with techniques widely used in studies of social behavior of infra-human primates. Occurrence of behavior fitting the definitions of each of six categories of object behavior and nine categories of social behavior is noted once during each 15-second interval. The number of recorded intervals in a 15-minute session provides the basic scoring unit. Observer reliabilities were estimated from paired data for four observers. Thirty-eight Negro and Caucasian children, ages three through five years, were observed in 3-child play groups. Median reliabilities of .95 and .81 were obtained for object and social behavior categories respectively. (Author/CK)