Sex role typing in the preschool child is the subject of this research report. Specific topics considered are sex differences, awareness of sex differences, sex role preferences, parent preferences, sex role identification, and family variables related to sex role typing. This summary of research studies in the field reports experimental and observational findings about behavior and characteristics typical of white middle class boys and girls between the ages of three and five. However, conflicting results of the research make firm generalizations impossible. It is suggested that standard tests of sex role preference and identification are of little value and may not be valid instruments. Although children were aware of and showed sex-appropriate behavior, the factors responsible for this sex role typing have not been identified. Further research is suggested to investigate the growth of sex role identity in children. A theory of sex role development is also called for. A nine-page bibliography is included in the report. (MS)