Studies were conducted with children ages 7 to 12 years to develop an instrument to measure children's health locus of control. Findings provide evidence that the Children's Health Locus of Control scale has acceptable levels of reliability, internal consistency, and construct validity. Item analysis and factor analysis were performed to determine item effectiveness and existence of significant subscales. Implications of this research for health education of children are disscussed. Links between the theoretical basis for the locus of control construct and a more comprehensive explanation of health behavior are outlined.