In this study, the effect of the Mathematics Bag Early Education Program (MAÇEP) on the mathematics skills (number/counting, geometry, measurement) of 57-69-month-old preschool children was investigated. A quasi-experimental design with a pretest, posttest, follow-up test, and control group were used in the study. The study group consisted of 22 children attending preschool education and their parents. In the study, MACEP was applied to the experimental group in the form of 50 activities for 12 wk outside the preschool education program. Data were collected using the Early Mathematics Test (EMAT) and Parent Focus Group Interview Form. Mann Whitney U Test, Wilcoxon Signed Rank Test, Friedman Test and content analysis were used to analyze the data. At the end of the study, it was determined that MACEP effectively improved the mathematics skills (number/counting, geometry, measurement) of 57-69-month-old children in the experimental group and the retention continued after the experimental period.