The purposes of this study were to develop a culture specific critical thinking ability test for 6, 7, and 8. grade students in Turkey and to use it as an assessment instrument for giftedness. For these purposes, item pool involving 22 items was formed by writing items focusing on the current and common events presented in (Turkish) media from 2009 to 2011, general home problems and problems regarding to school, and by considering aspects of critical thinking dispositions which were stated by Facione (2000). The dispositions were considered as cognitive factors. The data was collected by applying the test to 162 ordinary and 65 gifted students who were enrolled in the middle and small scale elementary schools of East Anatolian Region of Turkey. The data on the instrument was analyzed for gathering reliability and validity evidence by using "Confirmatory Factor Analysis," "Predictive Validity Analysis" and "Cronbach Alpha" reliability analysis. The results showed that reliability (a = 0.77) and validity evidence was enough to say that the instrument (Koksal's Critical Thinking Ability Test) is appropriate to measure critical thinking ability of the elementary students. It was found the test was appropriate to discriminate gifted students from their ordinary counterparts.