The influence of age, sex, representational detail of objects (prototypicality) and adult play suggestions on children's progression of pretend behaviors was studied. A checklist was developed and utilized for coding the responses of 20 children (10 males, 10 females), to objects judged to be high and low prototypical by 12 adults. Children ranged in age 20 to 33 months; mean age was 26.75 months. All children were Anglo and middle socioeconomic status. Presentation of the objects to each child involved four phases: (1) high prototypical objects without adult play suggestions; (2) high prototypical objects with adult play suggestions; (3) low prototypical objects without adult play suggestions; and (4) low prototypical objects with adult play suggestions. All four phases of the procedure for each child were recorded on videotape and coded by three raters trained to use the checklist. Significant differences in children's response frequency were found for age and play suggestions and between younger and older children's demonstrations of responses within the upper levels of the checklist. Results indicated that both age and the use of adult play suggestions influence children's responsiveness to high and low prototypical objects and, consequently, are necessary considerations in attempting to delineate the progression of pretend in late infancy. (Author/MP)