This paper discusses a range of computer applications in preschools, provides a rationale for the use of computers with young children, defines characteristics of effective computer mediated learning for young children and reports on a number of research activities in which the author and colleagues are involved. Answers are given to a range of important questions. For example, will children voluntarily use computers, how frequently, and will they be able to use them efficiently and remain on task? Do computers encourage independent play and discourage parallel and cooperative play? Is the computer motivational and does it help to focus learning? And is an adult's presence at the computer necessary, or desirable?