This guide to using computers with infants and toddlers was developed by the "Let's Play! Project," a 3-year federally supported project that worked to promote play in infants and toddlers with disabilities through the use of assistive technology. Following an introductory section on getting ready to use the computer with a young child, the first section focuses on software for the emerging play behavior of making things happen. Topics include selecting software, software features, what the parent should do, controlling software, and software for exploring causality, using a single switch. A table offers suggestions for single switch interfaces and/or mouse click. The next section focuses on software for exploring choices including controlling software and adjusting mouse pointers. A table describes suggested trackballs and touch screens for young children. The final section is on software for purposeful choice making and discusses controlling software and examples of alternate computer input. A table lists some suggested devices for early choice making. The final section is a directory of software for early intervention and is coded by its use in three types of play: exploratory choices, choice making, and purposeful choices. (DB)