Introduction The aim of this research is to construct, and to evaluate the validity and reliability of Caring Thinking Skill (CTS) questionnaire based on ‘ Philosophy for Children’ educational approach, for first high school students in Tehran. Caring Thinking is a one of "higher-order" thinking in Lipman's tripartite educational approach besides critical and creative thinking. Caring Thinking is the thinking skill which attends to what we take to be important, what we care about, what demands, requires or needs us to think about it. It is thinking about what can be done in the world for making better world. Unlike the importance and necessity of fostering this thinking to create a better world in future from childhood, unfortunately there has not been a tool to measure the quality of Caring Thinking Skill yet, and this lack of tools Led to the researcher's reluctance to study the level of this skill and their interventions to improve it in students. Method For this purpose, a pilot study was carried out on 60 students. Then, 742 students (358 girls and 384 boys) were selected by cluster sampling method and CTS questionnaire in Five subscales, including Valuative Thinking, Emotional Thinking, Normative Thinking, Active Thinking and Empathic Thinking, were distributed among them and the results were interpreted and analyzed. Content validity of the questionnaire was assessed by 16 indoor and foreign professors. The Structural Validity of this test was also evaluated by using Exploratory Factor Analysis and Confirmatory Factor Analysis. The findings indicated the content validity was appropriate (CVR = 0. 87), and in the construct validity, according to the results of EFA, 29 questions were deleted and the validity of the 60-item test was confirmed. Finally, from each of the sub skills, five questions that were the most frequent factors were selected and the form of the 25 questions was verified by using CFA. The findings also showed a significant difference between Caring Thinking, Valuative Thinking, Emotional Thinking and Normative Thinking skills in boys and girls. Results This research results indicated that the CTS questionnaire provides information on general skills and five sub skills, and can be used to measure and develop this skill for first high school students. Discussion Caring Thinking is bridge between cognition and emotion and personal values while care about collective vallues. Pedagogical caring is different from the common-sense definition of care, which means emotional attachment to someone or something, For Lipman and Sharp, caring thinking aims at judgments about what is of value, and how that which is valuable may be promoted, preserved, enhanced, or better appreciated. Lipman had been insisting on the addition of caring thinking to critical and creative thinking in higher-order thinking for two major reasons: first, Caring has ample credentials as a cognitive enterprise, even though it consists of low visibility mental acts; second, without caring, higher-order thinking is devoid of a values component. If higher-order thinking does not contain valuing or valuation, it is liable to approach its subject matters apathetically, indifferently, and uncaringly, and this means it would be diffident even about inquiry itself. As the findings of this study showed that, Caring Thinking Skill (CTS) questionnaire that was made and normed in Tehran, can use for study this skill in students and measure the effect some interventions same as participation in Community of Philosophical Inquiries to improve it.