This guide is intended to be used in conjunction with the third module of the Program for Infant/Toddler Caregivers (PITC), a four-module video training course for providers of family and center day care. The videos illustrate key concepts and caregiving techniques for a specific area of care, and the guides provide extensive in-depth coverage of each topic. This guide focuses on intellectual development during infancy, with an emphasis both on the types of activities that are naturally interesting to infants and toddlers and on the influences of responsive caregiving, the environment, and play materials on early development. Section One, "Cognitive Development," explores the intellectual activity of infancy (such as the use of reflexes and active experimentation), six discoveries of infancy (such as learning that events are caused and how objects fill space), and facilitating cognitive development through caregiver responsiveness. Section Two, "Learning Environments," discusses the role of the physical environment in influencing the development of infants and toddlers and providing appropriate physical environments. Section Three, "Developmental Milestones," explores the stages of development from birth to age three. Section Four, "Appropriate and Inappropriate Practices," illustrates contrasting caregiver practices in fostering cognitive development in infants and toddlers. Section Five, "Suggested Resources," lists books, articles, and audiovisual material. Contains 48 references. (EV)