The Child Observation in Preschools (COP) is a system for observing children’s behavior in preschool classrooms across a day-long visit. The purpose of using the COP system is to provide specific information about how each child in a classroom spends his/her time. Although other observational tools examine the classroom from a top-down perspective, focusing on how the classroom is organized as a whole (e.g., what the teacher’s focus or intent is, how involved children are as a group), the COP allows for detailed glimpses into the classroom experience of the individual child. The COP is based on a series of snapshots of children’s behavior across a period of time. Each snapshot may be, by itself, an unreliable piece of information, but collectively, they combine to provide a picture of how children are spending their time in a classroom (as an aggregate), as well as information about individual differences in children’s experiences. This manual is designed to introduce COP observers to the categories and codes used, as well as providing detailed examples of how children’s behaviors are coded in classrooms. It includes sample scenarios designed to illustrate how the codes are used, as well as the subtle differences that distinguish how codes are applied in different scenarios. There is also a supplement to this manual that includes videos taken from real classrooms with detailed information about coding. (author abstract)