Current interest and controversy about the use of microcomputers with young children led to a study of 13 3- to 5-year-old girls and boys enrolled at the De Anza College Child Development Center in Cupertino, California. Designed to determine the effectiveness of the computer in enhancing language experiences and development of cooperative play among preschool children, the study used guidelines intended to maximize the children's participation in social and cooperative play behavior while at the computer. Subjects were videotaped for 6 consecutive weeks as they played at either an Apple IIe microcomputer or two of four non-computer activities: playdough, blocks, art with coloring pens, or a fishing game. Counts were made of language events and cooperative play among the children in both computer and non-computer activities. The results of the study indicate that language activity, measured as words spoken per minute, was almost twice as high at the computer as at any of the other activities. Frequency of cooperative play at the computer and fishing game were comparably high--96% and 98% respectively. Cooperative play at blocks was 27%, at playdough, 14%, and at coloring pens, 8%. Although cooperative play at the computer was slightly lower than at the fishing game, the computer was the only activity that resulted in high levels of both language development and cooperative play simultaneously. Appendices contain a summary of the guidelines and procedures used for the study, a form for evaluating software, and tables and figures. (JB)