The purpose of this study was to develop a method for assessing aspects of the cognitive functioning of young children from their symbolic play. Subjects were 60 children, aged 3 to 5 years, from middle-class and lower-class families. The study was conducted in two phases, with the following objectives: (1) to identify and analyze aspects of cognitive functioning to be studied from classroom observation, and (2) to investigate developmental changes in symbolic play and assess cognitive functioning levels. A secondary aim of the latter phase was to compare the play of middle-class and lower-class children. Data were collected through written observer narratives. In Phase I observers described as many verbal and nonverbal behaviors (including interactions with others) as possible. Analysis of the data resulted in the identification of three aspects of cognitive functioning for classroom observation of symbolic play: symbolic representation, involvement and language. These aspects were studied in Phase II. A guide for recording symbolic play and a manual of procedures for analysis of symbolic play were developed; both are included in the appendices. Investigation of developmental changes in group play found trends in 11 of 30 categories studied, some in each of the three cognitive areas. The symbolic play of middle-class children was found to be similar in quality to that of lower-class children. (Author/BF)