Occupational performance assessments of children are essential for guiding occupational therapy intervention and for measuring the effectiveness of occupational therapy services for children. A review of relevant research and of occupational performance assessments designed for children was conducted to determine and describe how the occupational performance of children has been conceptualized and measured. The results indicated that more consistency with the ways in which occupational performance is being conceptualized by occupational scientists and within the occupational therapy profession is needed. A conceptual model for understanding and defining occupational performance was proposed and described. This model may be useful for assisting researchers in the development of new instruments for measuring occupational performance. In addition, how the model may be used by occupational therapists to describe what they refer to as occupational performance and to guide their evaluations of children are discussed.