In this paper, the authors take a distinctively developmental approach and draw on existing conceptual models and research for adolescence and middle childhood to identify domains and constructs that describe the health and well-being of the middle childhood population. This paper (1) reviews and synthesizes relevant existing conceptual frameworks (generally developed for adolescents in the U.S.) that could be adapted for the middle childhood population, (2) outlines considerations for identifying multiple domains of functioning within the child and specifies multiple contexts of influence for a middle childhood monitoring system, (3) proposes criteria for identifying constructs and indicators, and (4) suggests potential constructs and indicators to be reviewed by various stakeholders. This paper is the first of two papers in a multi-stage process of creating such a monitoring system.