The objective of this work was to assess the quality of life of children aged 6 to 12 years old. The authors present the different conceptual and operational steps which lead to the construction of a prototype tool. It was a generic tool composed of 63 items which covered the classically described areas of life. Its originality was due to the method of construction used which included children's involvement, to the pictorial representation of real-life situations for children, and to its adaptation for gender. The evaluation of this tool showed a good level of acceptability but statistical analysis revealed some metrological inadequacies leading to the reconsideration of the initial concepts and their methods of exploration. Therefore a new tool was constructed whose validation is presented in a second article in the next issue.