The objective of this study is to perform a validity and reliability examination of Number Sense Screener (NSS) by applying it to Turkish children aged 72-83 months. The universe of this general survey model study was constituted by 72-83-month old children showing normal development and studying at primary schools under the authority of the Ministry of National Education in central Afyonkarahisar province, Turkey. In sample selection, primary schools with different socioeconomic levels (low, medium, and high) were determined by taking into account the representation capability of the universe in Afyonkarahisar province, Turkey, and 672 children were selected from these schools through systematic sampling method. Validity and reliability studies were carried out using data from the NSS application. In light of the performed analyses, the difficulty and discrimination indexes of the items of NSS have been determined to range between 0.38 and 0.97, and 0.16 and 0.64, respectively. The reliability coefficients calculated for the whole of NSS have been determined to be between 0.876 and 0.884. The infit and outfit statistics of the items of NSS have been concluded to be extremely good. In DIF analysis performed in order to determine whether the items of NSS are gender-biased, the scale items have been concluded to be unbiased.