The purpose of this study is to develop a valid and reliable data collection tool to assess the decision-making skills of children at the age of 5 to 6. The study group is composed of 300 children attending independent pre-schools located in the central district of Amasya province and their parents. In the study, four-factor and 29-item "Decision-Making Skills Instrument-Child Form" involving "yes" and "no" answers and Likert-type single-factor and nine-item "Decision-Making Skills Instrument-Parent Form" aimed at assessing children's decision making skills based on the parents' impressions involving the answers "never," "sometimes," "sometimes," "often," and "always" were developed. The findings showed that "Decision-Making Skills Instrument-Child Form" consisting 29 items and "Decision-Making Skills Instrument-Parent Form" consisting 9 items are reliable and valid measurement tools.